My old Crosman 2100 Classic .177
This thing has been an absolutely intense ground squirrel cleaner outer.
It is the definition of a cheap air rifle. But, it is also extremely light, and, extremely accurate.
I bought it 20 years ago. But, when I bought it, I had nowhere to sight it in, living in a condo complex. So, it sat for long periods. Then we moved here, into the wild lands, and I met headlong with the mother ship of ground squirrels. You can literally see their den from outer space.
It was so bad with rodents, that whenever we stepped outside, you'd see a half dozen of them running in all directions.
So, since I went from a condo complex tightness, to, open lands, I broke out my 2100, and, put some spit on the front sight to make it shine nice, and I started plugging ground squirrels. I took out hundreds of them with this thing. Then it started to lose some pop, to a point of hearing more hammer firing spring than pop.
OK,... the 2100, when new, is only $65, shipped. You just throw out the old, and buy a new one, right?
No I.
I researched, and found a vendor with all new air handling parts, and I ordered a "kit" from him.
The kit was the main air valve, which holds the air, and releases it. A "pump cup" which is what imparts the air into the valve. And an exhaust seal that goes between the valve and the barrel.
This is the trio of parts that I replaced. It is the valve (silver), and its matching pump cup, that pushes air into the valve with each stroke of the pumping forearm.
The exhaust seal is in the valve body in this image:
The rebuild was fiarly simple, if you have 3.5 hands to work with; you will need all 3.5 hands.
I also found a fiber optic front sight replacement, and installed that. The orignal was all black, and, it was getting difficult to see it when I was in shaded area, looking out at bright sunny areas. I had painted it base white on the viewable face, with a bright neon pink top 1/3. This helped in sighting. But when I found the fiber optic replacement, it got the nod.