@Lilian , tissue paper may well work but then there is the bother of getting all of it out from the stitching.
I've had the 5 thread version of this machine for a few years now and had no problems with it at all. I went out to buy a Janome one, but the Brother came with the clear foot, (optional extra for Janome) and uses standard sewing machine needles, ( the Janome uses 'overlocker' needles) so I was persuaded. As for not being used much in 2 years, it may be that the original owner hasn't sewn as much jersey/stretch fabric as she'd envisaged that she would.