There's not a lot left to check other than the refridgerant. Are there any tell tale signs of leakage i.e. a white powdery deposit?. If the refridgerant is down in quantity/pressure it won't cycle properly.
Chat up your local landlord and find out which mobile refridgeration engineer services his coolers- he might be able to help you out with the right inducement.
Cledlyn
August 2008