It looks like it's good to go.
if it holds air there no reason to replace the o-rings/seals unless for peace of mind knowing they're new.try MaD.
if you feel the need
here's a good cheap way of making a valve tool DIY Valve Tool
disassembly PGP Non-Cartridge Valve Disassembly
The biggest thing you can do to it to make a difference would be getting/doing a valve job to it.you'll gain around 10 more shots per 12 gram.
it requires the gun and valve and body to be drilled and sometimes soldered on a tiny bit.
there's people on here that can do this for you.me,WALZ,MaD,chipnstone.....palmers does too but they are $$$$ non-PPS Performance tuning
and making/buying a velocity adjuster. http://i52.photobucket.com/albums/g2...psfbb68a7c.jpg
I think the delrin pump handles are smoother than the aluminum ones. Sheridan Products F/S
that's the basics/