First, remove the stock and then remove the cocking linkage from the trigger group (open the barrel a little and tap the trigger assembly back). It should slide back and pop the whole thing out. Then remove the end cap and the spacer behind it.
Next you will remove the trigger group; it should just slide backwards out of the slot on the tube. Remember how it was laid in there for the sear position on the piston when you reassemble it. Take a picture. Next, the piston will slide out, then clean out all the oil. File the inner edges of the cocking slot and trigger group opening. Then use 220 grit sand paper taped and wrapped around a wood dowel. The cocking shoe has sharp corners and edges, lightly file those off so as not to affect it's size/fit in the piston then lube it with moly. File the rough/sharp edges on piston, including slightly rounding over the edges of both ends of so as not to have a sharp edge rubbing in the bore. Then sand the piston outside lengthwise to help it store lube. Coat the outside of the piston and seal with silicone grease (or moly) and wipe off excess.
The new seal goes on easy after coating it with silicone grease. I found the need to heat it, just to get it pliable so it goes easily over the end of the piston then push the piston, seal first, down onto a paper towel on a work bench. The seal pops right into place with a nice snug fit. Clean oil out of combustion chamber then swab with silicone (or moly) grease, and then wipe out the excess with a dry swab. Use moly grease on both ends of the ram and the cocking shoe and cocking slot edges. Deburr all other stamped parts with a file, then clean and lube. Also deburr and lube the linkage parts. Carefully slide the seal past the trigger group openings and cocking slot. Then put back together in reverse order.
