Trunk Lock

I had a mechanic who took it upon himself to "adjust" the vacuum lock system on my 1981 240D. Granted, one of the locks gets sluggish from time to time, but now I can't open my trunk. I am wondering if it is the vacuum system or the lock itself. Is this something I can check or adjust myself? I am pretty handy for a girl, but not a greasemonkey. How much should the repair cost?
I live in NYC, but now use a fairly good one in Glen Cove, Long Island. Thanks in advance for your help.