Wagner 505 paint sprayer

[shop hermit]

I know this question is a stretch from the normal theme of this forum, but I have been all over the net and this is a last resort. Has anybody replaced the diaphragm in a 505 Wagner paint sprayer? I bought a used one at an auction and the guy said he thought it needed a new diaphragm. It was pretty obvious where it was located, so I took off the pump head and of course all the fluid between it and the piston ran out. I ordered an new diaphragm (the old one looked ok) and a quart of wagner hydraulic fluid. I didn't have a manual, so I looked on line for one before reassembling it and the first thing I found was a picture of the head with the warning NEVER REMOVE THESE 4 BOLTS (which I had already done) Is there anything I should know before filling the diaphragm cavity with fluid and replacing the head? Everything I can find advises to return it to a Wagner service place to have diaphragm serviced. I can't see any obvious reason for this unless there is some special procedure to insure that there is no air entrapped in the fluid. Anybody been there and done that???

[mike os]

might be worth talking to a hire company tech... they usually know this stuff