[TenTec] OMNI VI+ lost 12m

[Don Rasmussen]

Hi Guys,
All bands good except 12m, no Rx or Tx upon bandswitch. It's a recent happening, the latest TT service was to replace 10m crystals, 2 of them had gone bad with age. This time I am not hearing the crystal trying to lock when the band switches, so more inclined to suspect the PIN diodes rather than the crystals. I suppose the 12m crystal could be fully failed. 
Anyone have any suggestions on what to look for?
Also wondering if anyone has a 12m crystal from a parts OMNI VI+ before calling Paul for part or service.
tia Don...