I have a Beeman RS2 (same thing as TF89, Force 1000, Hammerli Titan, etc...) that I tore down recently. The seal is synthetic. Be aware that the trigger group is what the spring guide is resting against so you'll need to fabricate a tool to get around the trigger group and pins to relieve spring tension before driving out the two front pins. Its kind of tricky the first time you try it. GTA member 70GTvert made a very good tool for the job out of a deep-well socket using a grinder. Also, don't try it without a spring compressor, the spring has quite a bit of preload! The pins only come out one way, one side is knurled and one side smooth - drive them out from the smooth side. Based on what I found inside mine I would recommend that you deburr the cocking slot and trigger group cutout as best you can before you pull the piston to avoid cutting the seal on the way out. I polished the spring ends, tophat, and rear thrust washer with fine grit sandpaper and did a more-or-less standard lube job on mine. Made a world of difference and I got a pretty decent increase in power as well.