Its been a long time but it seams like that is part of the piston. You put it in there I suppose. There are 2 small bypass holes in the bottom of the reservoir. Make sure they are open. One is very small. You may need to run a tag wire through it.
George
Last edited by Wrenchbender Ret.; 01/28/2022 4:55 PM. Reason: Reservoir instead of cyl.