Loose focus on Omega B-600
I was recently given an Omega B-600 enlarger by a photographer in town who's switched completely digital. (his loss!) All in all, it works great as a starter enlarger, and I've been having a blast learning the basics of printing in my makeshift darkroom. The thing seems in good enough shape, considering it was heavily used for 20 years or so.
However, the focus knob on the enlarger is very loose: often when I'm adjusting focus, the lensboard will slip and fall a little bit, which can make getting a negative in focus more difficult that in needs to be. It only happens when I'm actually adjusting focus; once I actually get the thing in focus and leave it, I haven't had any problems with the focus slipping. I'm sure this is just the result of a lot of wear on the focusing assembly.
Is there anything I can do to repair this? I've googled around and found some people talking about tightening the knob, but haven't found anything specifically about a B-600 or instructions on how to do so. Any information y'all have is appreciated.
And if not, hey, free enlarger is free enlarger. I'm confident I can manage until it's time for an upgrade at some point down the road.