The "thingy" is called a "trip" and as Rabbit said the trip and/or its spring are missing, or the trip is worn. Just so you know, the small frame trip is different than the 12 gauge version. 12 gauge trips are hard enough to find; small gauge is going to be tough. If you buy the gun you'll probably hve to get one made by reference to another smallbore trip.

IMO, that price for the gun is a little steep in the condition you described. Silvers

I AM SILVERS, NOT SLIVER = two different members. I'm in the northeast, the other member is in MT.