Can you turn the balance wheel by hand? Needle moves up and down? If it's been in storage for ages the motor pulley is known to be a bit slow at first too, turning the hand wheel by hand can help making sure the pulley turns a few times. A lot depends on oiling and cleaning the machine in general. The motor can take a single drop of oil on each of the grease wicks; it will hopefully reach the ends of the motor axl. It's a bit worrysome to oil a motor like this, and it really should not be oiled in general, but a single drop can work wonders on old dried up grease wicks.
I don't know if you know the 99 well, but there is one thing with the bobbin case; slide the bobbin cover off completely, lift the lever slightly up and towards you, it will release the bobbin case for cleaning and oiling. Don't mess with the screw in front of the bobbin case unless you have to and are prepared to spend quite some time with the service manual for aligning parts correctly. It will mess up tread tension if it doesn't go back right.
Last edited by Mickey2; 12-03-2017 at 09:00 AM.