The right leg adjuster knob (black .. plastic... I don't think they have it) lost that on my fork a long time ago... but the good news is: it's not an essential part of the fork, if you want to adjust the rebound you need an allen key to get in there and give it a couple of clicks. Shocktech have the high pressure seal (it's made to order I think cost me around 30$ plus shipping from New Zealand). My question is: how confident are you in your wrenching abilities? This operation does require taking apart the lower damper shaft (shim stacks and all) as the high pressure seal goes only in one direction (top to bottom) and if you try to insert it the other way (in order to avoid taking the top piston apart) you will ruin the seal and have to start over again (learned that lesson the HARD way