Another KX 125 question-Volume

I bought my C152 in 2002 with a KX 125 and a KT 76A. In 2004, I had an
avionics shop move them to the bottom of the stack along with the associated
course deviation indicator. The top of the stack is filled (truly) with a
PMA6000M-C, a KY 196A, and a KNS 80 connected to a KI 206. It worked great
for two years. I did need to shut up during approaches as I had the problem
stated in another thread with respect to off flag and indicator going off for
the KNS 80 navigation receiver. I had not considered that enough of a problem
to go further and thought that is was going to be an expensive shielding
problem as the other thread suggested for the KX 125.

The avionics shop that did the 2004 install went out of business in 2005 when
the owner died. He just did installs and I had not noticed the navigation
receiver problem before then. I do not trust the closest shop that does
testing as they have charged me big dollars for very little value provided to
me. There hanger is full of big iron all of the time, so I felt like it was
their way of saying "don't come back".

To the current concern. About 6 months ago (2008) the KX 125's 25KHz knob
dropped off and the radio was removed to retrieve the knob and replace it on
the shaft. No testing was done as I just had a local install shop help me.
They do very little testing and send most of it out to a shop a day or two
away by UPS. They do not really like the closest testing shop either. I had
NO problem with volume until several flight hours after the re-install. Now I
have to turn the volume on the KX 125 all the way up to barely hear it for
most frequencies. It is louder on some frequencies than others. I had the
radio pulled during annual this week and had the connection contacts visually
checked. There did not seem to be a problem according to my AI's visual
inspection, but I still have insufficient volume. It seemed to improve a very
small amount, but that may have been wishfully hoping on my part. The KY 196A
has no similar problem.

I have also had to replace the KNS 80 due to other problems about the same
time as the volume problem. An avionics shop (two days away by UPS) tried to
repair the intermittent drop out of all of the saved information and
duplicated the problem on the bench. They could not repair it, but still
charged me $150 for their time and some parts. Without a yellow tag, it is a
boat anchor. I just bought another one from a different avionics shop's
internet site and R&R'd with my local installer. With the replacement, a
lower serial number by about 200 in the 16,000 range, that navigation
receiver "seemed" to have less of an interference problem. I have not tried
an ILS with it, yet.

A new shop (one day away by UPS) to whom I talked, and from whom I purchased
the replacement KNS 80, suggested the PMA6000 be sent first for a $30 bench
check. This is a better check estimate as the shop two days away want $120 to
just look at it, again with no repair ability as part of the deal. I am
concerned that I am chasing avionics gremlins. I am wondering whether to send
the PMA6000, the KX 125 (optional first step), both, or the whole airplane to
the radio shop one day away? They are only open when my wife and I are at
work, but it is only a 1 hour flight and 2.5 hour drive.