S13 Manual Transmission Repair Question

[GymkhanaS13]

I am hoping someone can help me out here. I just got a S13 manual transmission for free. I have an auto, so I am going to swap it over soon...The reason I got free was because the guy who had it before me said that it slipped out of 4th gear 2 times over a period of a few weeks...He also had a bad clutch. When he replaced the clutch he had an extra tans so he swapped it in. I called some transmission shops and they said they would look at for free to tell me what is wrong with it. I just don't want to get burned by a shop for work the trans may not need. Can anyone give me some advice to troubleshoot this a little before I take it in to a shop? Thanks again!!

[biggie]

Easiest/Cheapest route will be to buy a known good 5spd transmission for $100 or less.

You can have the shop look at it for free, but if things are slipping it probably could use a rebuild.