Aperature release on old camera broken?

[Garbz]

I have an old Tamron 35-70mm lens. The one I use the most as I don't wish to buy a new one. (saving up for better toys ).

Anyway I dismounted it from the camera today and the aperature didn't close, it was on f22. A quick tap and it did again. I played with the aperature release a bit opening and letting it flick closed and I noticed that it moves incredibly slowly and often even seems to get stuck.

My question is during a camera's normal operation are there any additional forces involved in closing the aperature on old SLR cameras (pre autofocus)? My guess the way it's floppy right now is that the aperature wouldn't close in the 1/1000th of a second it takes for the shutter to do it's work.

Oh my other lenses move instantainiously.