I have a 99k too, although I rarely use it, mainly because the 201k is always set up for use. The 99k is a lovely machine, and, dare I say it? nicer to use than the Featherweight - although that has its own charm.
Mine has a knee controller, and is sooooo quiet.
Not much to go wrong, although the tension sometimes needs attention. There are lots of tutorials for this online.
Jessie