There's a good chance that it's the old capacitor that has blown. Sometimes they just fail quietly, other times it's a bit more spectacular. Can't remember the capacitor configuration in the 800 series **but basically they aren't needed today as they were there to minimise intereference with AM radios and old analogue TV.
Often they fail "open" so the machine will run without it anyway.
Any sewing machine repair man will have dealt with hundreds of these - they are old and fail all the time. The cost of fixing it is likely to be not much, so don't think you have a disaster on your hands.
** I'll try to find time to have a look later.

I'll try to remember to "de-fluff" as well 

Shame the 8nn Berninas don't do a triple stitch - don't think they had developed the automatic back and forth of the feed dogs then. Even when they did, the Elna cam system is much more versatile.

The triple stitch is a nightmare if you get it wrong, I agree.

If in doubt about how a seam is going to turn out I sometime haul out the New Home/Janome 609 - it weighs a ton, but if you replace the bobbin with the looper thingie that came with it, it'll also do a chain stitch which is great as a try-out stitch before you commit to the final seam as it just pulls out in one go.

Oh - I discovered by accident, that all of the Elna cams that do back and forth will also do a straight stitch....if you forget to set the zig-zag that is 


Edit - umm - no - I'm getting mixed up - it's the Husqvarna Viking ones that will do that.....too many machines...Doh !

Okay - here are the words of my 'expert' - scratching round at the back of his retired head  LOL 

"Capacitors, as well as preventing interference, also protect the motor and foot pedal from the effects of a back EMF. The back EMF can cause the pedal or motor to short out. Back EMF occurs when the motor stops, so every time you're sewing, and stop the work."

So if you're planing on using a vintage machine, it needs new capacitors 

I wouldn't have recommended removing the capacitor, or indeed done so myself, if it hadn't been based on expert advice from a Bernina Certified Technician on a Bernina Vintage machine group. He was succinct - "Just chuck it".

I think you may be talking about a different type of motor. Old machines like the one queried on here have a mains voltage brushed universal AC motor.  If the power to them is stopped the magnetic fields in the rotor and stator collapse immediately so if they continue to rotate from inertia there is no back emf created.

The DC motors in modern machines are a different matter and have sophisticated circuitry to control them.

You can easily replace the capacitors if you want to - the single ones are just pennies, the "3 in a single tube" are more expensive, but readily available on ebay.

The mechanical Berninas - the "Records" were beautifully engineered machines. We have 4 of them ! (a 600, a 730, an 801, and a 900 Nova). They are a delight to use, and about as smooth as any oscillating hook machine can be made, although I wouldn't want to futz around doing buttonholes on the 600 or even the 730.....

My experience of the 1000 series machines, is confined to the AC motor versions - 1008, 1011, and although they stitch superbly, I find them noisy and grumbly. My local Bernina dealer who I've got to know fairly well reluctantly agrees with me. Never used a 1020/30/80 and I expect the more advanced DC motor machines in that series are much smoother.

I used to have the Berninas as my favourite mechanical machines to use until I got an Elna Star SU. Full rotary hook and even smoother than the Berninas as a result. Motor purrs away, and the hook mechanism is next to silent. Engineering well on a par with Berninas, and perhaps a little better in some ways. (I service all our machines myself).

Don't know why Elna Star machines aren't held in such high regard - perhaps much lower volumes sold, but if you ever have a chance to use one in good condition I think you'd be sold ! One advantage is that they tend to command lower prices in the 2nd hand market, and there are real bargains.

If the treadle machine is the Singer 15 you mentioned earlier, I'd definitely give it a shot. The old saying was that if you can get it under the foot it will sew it. They are heavily built, and I doubt you'd do any damage either way.
The 730 (I assume you mean the record 730, not the Artista 730) is a beautifully engineered machine like all the Records, but if your 611G is already having problems I sorta think it could be abusing the Bernina if you use it for too much heavy work.

The right needle could be a game changer, but I guess you've already sorted that ? Sounds like you'd need something like a sharp "jeans" needle of the right size. Also there are some that are designed for "sticky" fabrics like the Schmetz chrome or non-stick needles.

@keepitsimple Interesting to hear your 19e went through heavy fabric easily, I'm finding mine struggles to start sewing through leather and I have to turn the wheel by hand to start it off.  It's worse in the low gear.  I'm wondering if something is slipping and not driving the needle down, is that a possibility?

Definitely something amiss if it struggles in low gear. People often recommend putting the needle down in the fabric to start any machine, but I haven't found that at all necessary. I presume you're using a suitable needle ? that's essential.

There are 2 belts IIRC. One goes from the motor to the low speed/high speed gear box, and the other from the gearbox to the main shaft at the top that drives the needle. One or the other could be slipping I guess. I suppose you would hear the motor still turning, but no needle bar movement in that case. Does the machine sew well for lighter stuff or is it a bit sluggish ?
There is a host of information and expertise available on the Pre-1980 Husqvarnas group. Someone will be sure to help if you ask.

https://groups.io/g/vikingsewingmachinespre1980

You have to join to get full access, but it's easy to do and free. There is a mine of information - user manuals, service manuals, service bulletins etc.. and some real experts who are happy to help.

They cover the lightbulb. There is a small metal tab at the end of them on the left, and you can pull it down, either to change the bulb (LEd is a good idea as they don't get hot) or to direct the light more closely. At the right end there is a light switch.