TLC for Vintage Marantz Receiver in NYC Area

A few years ago, I paid a premium for a vintage (late 70's?) Marantz receiver which appeared to be (and was represented to be) in 99 point condition.

For a couple of years, it just sat on a shelf in my office where once in a while I would admire the blue glow of its dials.

Recently, I moved it into the house, where it is hooked up to the cable TV, DVD player and a pair of Epos 12 monitors.

In general, it has worked perfectly, is a joy to use, and has a nice warm, non fatiguing sound.

The left channel has developed an intermittant, staticky drop out, however. This seems to occur more often on the auxilliary input (where I have connected the DVD) but it seemed to also happen on FM.

It is the kind of thing that often goes away by slightly moving or tapping the receiver, turning the input selector back and forth, or even adjusting the volume up and down. So it is really maddening.

More maddening -- I have been screwed over in the NY area by techs and repairmen on vintage equipment and would therefore appreciate any advice - either on how I might diagnose and repair this myself, or if anyone knows an honest technician.

Here's something we rarely hear on Agon: my wife LOVES this component.

So any advice greatly appreciated and thank you very much.