Edit: beaten to it by truckcab, damn i'm slow at typing on the phone.
If your only polishing hammer real ect then there's no need to empty the air cylinder, the s400 series is incredibly easy to work on even for me , although I was shown how to do it.
If you don't feel competent I would get someone else to do it, or show you. which IMHO is the best way forward.
ps: ill see if I can find any vids for you.
Mark