Coinco 3340-s gremlin

I've got a Coinco 3340-s that is having a midlife crisis.  It has worked flawlessly for about a month, but last week started doing some strange things.  Like rejecting all coins but vending product after rejection.  Before that, it would never direct coins to the coin vault, even if the changer tubes were full.

Here's my question.  Does anyone know of a good repair shop for these units?  I've seen two vending companies that do flat rate exchanges of rebuilt units for $49, but am wondering if anyone has specific experience with any shops?  Stickers on the unit indicate it was last serviced by Coinco in September 2001.

I've already checked the unit for dirt, gum, and such lodged in the coin changer, and everything is clean.  I did find some paper lodged in a flapper towards the bottom of the unit (believe it's the shunt between the coin tubes and cash bin) but removing it didn't make much difference.  The prior owner indicated that the changer had "issues" when they had it, of course they told me it while I was loading my truck after paying for the machine.  '>  Oh, well.  Still a decent buy, even with the issues.  (The host machine is a early-90's Royal Vending 5 select electromechanical with coin changer and dollar bill validator).

I rigged up a free vend switch (love that frozen topic!) on the unit so I'm not desperate right now.  But would love to fix it correctly for use when company visits (even if I do leave a tub of quarters on top of the machine).