Re: Ts20
Start with that old gas. It probably is like molasses and stinks to high heaven by now. Plain old rubbing alcohol will clean it out. Take a look at the carburetor and hope that old gas wasn't in there too. It probably will need primer seals and a new float. Check the check valve in the carb (the big hex head part), and make sure it flows in one direction only.
Then clean the points. If it has the magneto that I think it has, take the points apart and clean each contact individually. Set them at .020" gap at their widest opening.
I believe that the TS is a TD without a recoil starter. Literally tons of TD's and TN's were built. TN has a neutral clutch.