RockShox Psylo oil replacement
Rebuild manuals seem available (see link in comments). Figure out what year the fork is and google for the appropriate document. If you can't find it contact RockShox, they should be able to provide you with what you need. 

Assuming the bike has not been ridden to the point where seals etc need replacing you should be able to just do a oil change.

If you have the tools and are confident you can do what the manual describes, go for it. If you mess up you can take it to the LSB.