Just jumping in on the above O-ring discussion.  You can buy this O-ring at most hydraulic hose supply shops for a lot less money than ordering it on-line.  The O-ring is 1 mm thick, with an 8 mm inner diameter. 

The hydraulic hose shop has sold me O-rings for hose reels and other things around the house and shop.  Often, given their volume, they would just give me a few O-rings because their cost was so low and it was too much effort to make up a receipt for $0.13.