Just guessing, but tinkering with the part under the epoxy would probably knock the scanner out of specifications. So they safeguarded it with something nearly impossible to remove.
The epoxy was added when ECPA ban was revised for the 870 MHz AMPS band.
Users learned that you could still receive cellular AMPS via images by tinkering with the bandpass stage(s).
That led the FCC to require stricter rules regarding the cellular block so the manufacturers added epoxy over the bandpass switching area of the boards so end users could no longer alter the bandpass switching.
This was covered in a revision to the original ECPA cellular ban.
No more diode adds/removals or hidden menus were allowed with the revision of the ECPA plus they covered the boards with epoxy so they could get FCC certification. Then of course you had hard coded chips so a user could not alter anything via a firmware change (hack).
It is bad as it does make repairs on that section of the board nearly impossible.
Icom is probably the worst as they just hard code out any frequencies that may allow a cellular image even if those frequencies fall within ranges that are not restricted.
Being as AMPS is long ago dead, that ECPA restriction should be lifted so component level repairs can be made if needed and manufacturers can stop producing USA and foreign versions of the same radio.
But... I would not be surprised to see further restrictions such as limiting access to the discriminator section using the same epoxy method.
Some manufacturers did cover sections of boards or seal tuning components but usually not with epoxy. Wax was the original tuning slug fix so values did not change from vibrations and such but that was only there to try and keep the radios aligned. Of course as other components aged, re-alignment was needed so you had to heat and soften the wax.
I truly miss those days.
I've seen some modern day equipment where they use something like super glue to fix coils in place. Stupid idea as you can't re-align those either unless you can find a solvent that will soften or remove whatever they used to fix a coil or other variable part. Oftentimes, the solvent will end up damaging other components.
But in this case, Uniden does offer their flat rate repair. They just replace the entire board which would be worth it for a 996XT in my eyes.
I often wonder if some manufacturers have a solvent that allows them to repair boards down to the component level being as they have the knowledge of what type of epoxy or whatever was used and may very well have a way of removing it.
edit: UPMan explained it in much simpler terms while I was typing my reply.
What he said holds true for anyone manufacturing radios that must be FCC certified.
