Actually, the most common part failure relating to that symptom is the breaking of the guide bolt (shifter bolt) in the shifter tower. A worn shifter sheet would cause the shifter to rise out of position and possibly disengage from or jam the shifting linkage inside the transmission.
The shifter bolt holds the shifter in place so that it does not rotate in it's socket when the shift lever is pushed from side-to-side. Most likely, your enthusiastic friend broke the tip off the end of this bolt. It probably fell down into the bottom of the case out of harms way.
If you remove the shifter boot and look at the top of the shift tower, you will see a bolt head on the rear of the tower assembly with the head facing the rear of the truck. This is the problem bolt.
There are two sizes of bolts - one for the pre-'89 transmission and one for the 89 and newer transmission (My model year might be off by one, but you get the idea...). The main differences between the two bolts is the diameter of the tip that fits into the shifter lever. The newer bolt is thicker so it does not break off easily! Unfortunately, if you buy the thicker-tipped bolt, it will not work with your shifter lever because the groove it fits into on the shift lever will be too narrow! You would need to machine the existing lever's groove wider or get the newer shift lever.
You can get a replacement bolt at your local Suzuki dealer or you can buy one for many of the aftermarket suzuki vendors. You can also find a replacement down at the salvage yard or pick-n-pull.
I think that both versions of shifter bolts can be removed with a 10mm box wrench but a 12mm might come in handy, too. I replaced my transmission two months ago and had to deal with the differences between the older and newer type of transmissions - and those bolts!
While you are at it, it might be a good idea to replace the shifter sheet as zooki4x4 suggested. Zuks Offroad (ZOR Zuks Off Road
) has a rugged brass unit that'll outlast the rest of the truck.
For more info on the transmission, download the '88 Samurai Factory Service Manual (FSM) at Ack's FAQ (link in signature, below). Do a search for fsm
UPDATE: There are two shifter sheets: one for the transmission and one for the transfer case (4x4 shifter). They are two non-interchangable components with the same basic function and name.
I hope that this helps!
searchable links to the Samurai/TracKick
info that you are looking for!
'88 Samurai Offroader - HypnoToad
'88.5 Samurai Tintop Restoration Project - Bad CR
'14 Ford Transit Connect DD