Spirit internal squelch adjustment for SP21, MV21, MV24, P10

[A10382]

Does anyone gave the instructs for adjustment of the squelch level on the 1 & 2W Spirit Hts?

I have 2 dozen radios that work OK. VHF MV21 & 24s, UHF SP21 with two of the GMRS freqs, etc. ALL of the radio work file except for 4 units.

One P10 VHF requires the squelch adjustment to be turned almost fully on to squelch the audio.

3 Sp21 (UHF) HTs (with 2 GMRS freqs) that intermittently open the squelch -- very annoying.

If there is an internal adjustment, I don't see one on the portion of the PCB exposed under the battery tray. If there is one on the PCB's upper half, how do I disaasemble the case fro access ? Are there screws under the plastic top of the radio to separate the shell? Do I have to peel the top plastic piece off for access to dissasemble.

Thx in advance for any info you might have.
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