Transmision problem

I have a 96 chevy lumina with the 3100 series engine.The transmission was working fine up till about 2 months ago.Now when I put it in gear it will not go in.If I put it in 1 st gear and rev the engine a little most of the time it will go in but slips during take off and when I stop,it ends up not wanting to go again.I have changed the filter and fluid.In the process of doing so,I found a very small micro screen in the pan.Could the vacume operated modulator be causing this.If not what would be the cause.Ready to junk it even tho the rest of the car is in pretty much exelent shape.

No vacuum modulator on this transmission. Those were eliminated years before this car was made. It’s probably electronically controlled. Transman 618 can confirm.

I think you have seals that have shrunk and hardened with age, at the very least. A can of Berryman’s B-7 Chemseal may be worth a shot.

Does the screen look like any one of these??

transman

Yes it does look like the 3rd one. The servo screen.What does that tell me and how easy or hard is it to fix if that is causing the problem.And in comment to the other.Yes this transmision does still have the vacume operated modulator valve.

The way it looks,no one can make any suggestions.I guess I couldnt hurt it any more than it is.What would happen if I put a can of stp oil treatment in it.

I guess no one knows what could be causing my problem.I am a pretty good mechanic,been doing it since about 1975,but when it comes to transmissions,I do not know much.I guess I could change the vacum opperated modulator valve and see what happens.Thanks anyway.