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It sounds like your PLL board needs a bit of adjustment.
The radio uses the same circuitry for every band, other than some band pass filters and front end tuning. The PLL boards frequencies change depending on which band you are on. The capacitors used did not have great tolerances and their values tend to change over time. The higher the frequency of operation, the more they will drift, to the point where the PLL can not lock.
Re-adjustment of the PLL by someone who knows what they are doing may help, but it would be better to have all of the VCO capacitors changed by someone competent to do this work. Just re-adjusting the PLL board will not guarantee that this problem will re-occur. Doing this can take a lot of time and work. Hopefully you have a good HAM friend that is technically competent and will help you out.
If the PLL is dead, it's almost not worth saving. Even if you get a replacement PLL and change it, the radio will not work right without an alignment. To align the radio you will need the factory alignment guide, watt meter, volt meter and an oscilloscope and a basic knowledge of electronics.
Depending on what you mean by "off frequency". The 29LTD, like all other 40-ch radios is PLL controlled, referenced to a 10.240 Mhz crystal. The channels are all mathematically synthesized by a higher frequency VCO and the PLL controller chip. If the PLL detects the frequency is not "locked on" it shuts down transmission. If the frequencies are there, but "out of band" then I suspect that there has been modifications done to the radio to make it so. If you want the radio back to stock, undo the mods. If the radio is out of band, and no mods present, then there is a problem with the PLL. Sometimes that may stem from someone getting into the radio and "tightening all the screws". (the shops just LOVE those!) If the channels are in band but seem a little off, there is some adjustment in the form of a small trimmer capacitor near the crystal. But to adjust it properly, you should employ a frequency counter.
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