The Jet 1236 and it’s HF clone make great starter lathes. Depending upon how much and what you turn may be the only wood lathe you ever need.
The Jet 1236, pretty much replaced by the Jet 1440 lathe.
So assume you buying a used Jet 1236 for $220. Basically you want a lathe that’s complete, no unusual noises, all levers, handles, wheels work and hold. Belts are serviceable.
Tool rest & base should not move once locked down. Push on them. Same goes for the tail stock. You really don’t to have to break out wrenches to lock stuff down when turning.
Check the lathe spindle by hand, should not have any free play or grinding noise when you rotate it.
You want to check head stock/tail stock alignment by inserting drive center in head stock and with live center in tail stock bring the tail stock up to the head stock and see if both centers meet dead on.. There are some simple adjustments that might take care of the problem, then again maybe not
Turn the lathe on. You don’t want to hear a bunch of noise when it’s running. This lathe comes with variable speed (reeves drive) should not make noise, or vibrate at different speeds when changing speeds without wood mounted.. Speed changes should be smooth up and down. .
You may end up with vibration problems later on with wood mounted in the lathe. Experience will tell you to lower or raise speed or add weight to the lathe.
Good luck!