[TenTec] Scout: Sidetone on SSB transmit

[Jim KO5V]

This is my first posting to this list, so I hope it works...

I just acquired a Scout that seems to work well, except for the sidetone when I press the mic button. It is identical in loudness to the tone I get when I press the key, or the tune switch. I saw a reference to badly dressed wiring in the archives, but I didn't find any other information. CW works just fine, power out is to spec, and the rig receives well. There is a surplus hole on the back (about 1/4" in diameter), under the meter switch, like some custom feature has been removed. There are also two, 1" diameter holes in the bottom cover (???). The seller was honest about the problem, and he included a receipt showing that the rig had been checked out by TT sometime in the past. Because of the two large holes, and the removed item, I wonder if there is an RF shielding problem, or butchered wiring somewhere. Any ideas of what to look for, or where to start are appreciated. 

Any direct replies might cause an automated response from my SPAM filter, so just please ignore it.

Thanks in advance, and Happy Thanksgiving!  73, Jim KO5V