There are several threads on this site that have dealt with this. I've gone as far as obtaining some garlock type seals that require only slight machining of the housing and would fit both sides of the shaft with the intent of at least being able to reseal them. After disassembling a spare unit, I've come to the conclusion that for the price (around 100 bucks exchange), you cannot beat World Wide Auto Parts(google NOS Imports)for a guaranteed rebuilt unit that has upgraded seals etc. It was fun, but not that much fun. There appear to be absolutely no parts for these units except the valve mechanism) through any of the usual and not so ususal vendors. They were made to be throw away items as far as I can tell.