Looks pretty dirty inside. I'd consider pulling the cards and cleaning each of them. At the same time look for any signs of bad capacitors, burnt parts etc. No need to mess with the actual RF parts yet. Practice ESD safe handling/cleaning techniques of course.
I would start by pulling all of the circuit cards and cleaning their edge connectors and their sockets and then reseating them and seeing that helps. AFTER doing that, pull the cards and clean and reseat all of the socketed ICs. While you have the cards out, LOOK at the capacitors but don't get ahead of yourself and start replacing any of them unless they are VERY obviously bad. Take one step at a time or else, when something fails, you'll have no idea what you did that caused it.
"Practice ESD safe handling/cleaning techniques" <<< Pay heed!
Get a manual and be sure that all of the cabling is plugged into the right connector. Some of these have many cables and it's easy for someone to plug one into the wrong connector. Hopefully no one has been inside of this one before. But if the seals are broken then there is no telling what kind of simple (or not so simple!) screwup that they may have made.
Probably THE first repair that I would make would be to replace the RIFA caps.