The drifting is the only thing people can find bad to say about it. This can easily be corrected with a proper alignment and tune. If not there is also other mods that can fix the problem.
There is nothing that can fix that problem that I am aware of. Not as yet anyway. Wish there was.
Even if one were to replace the reference crystal and the 1st and 2nd oscillator crystals with high quality crystals; they will still drift. The reason I discovered through research is due to the fact that the oscillator coils are too broad-banded and will change their inductance depending on temperature. If these coils cannot be stable due to temp; it is not the fault of the coil. It is due to the fact that the broad-band nature of the range they will tune that is an integral part of the engineered circuit. What they should/could have done is narrowed up that range up a bit. But they didn't. So, you and I must both use these radio knowing that temp is a factor to be reckoned with. Yes; I use a Galaxy DX-99V in my mobile in sunny, warm California and am aware of their problems only too well. But I still use it.
A proper alignment is done with this radio after the radio tech has it on the bench and left on for 30 minutes before he begins the alignment to the radio. It takes that long before it becomes stable. Usual cost for a full alignment is anywhere from $35-$45.
*At that point, he will start with adjusting the VCO voltage and 10.400mHz reference crystal.
*He will also peak the VCO frequency and check it on a o-scope to be sure that it is symmetrical and equal in height on ch 1 & 40.
*Then the adjustment of the first oscillators.
*Then the output oscillators.
*Then the tx transmit circuit coils after he adjusts the bias voltages for the driver and final output transistors.
*After that, he will adjust the AM modulation for ~100% and then the ALC (~16 watts PEP) for SSB mode.
*Then he will set the wattage for low dead key and high dead key watts (4 watts dead key and 16 watts PEP/AM).
*At this point, he will align the receive circuit for AM and SSB.
*Your meter gets adjusted last, so that it corresponds to SSB, AM, and receive for both TX and RX modes.
There are a couple more adjustments than what I mentioned (squelch, SSB balance, noise blanketer, freq counter, etc); but that is the pretty much what is involved with a true full alignment. A 'peak and tune' involves just the TX coils, the modulation, and the ALC - plus re-adjusting the meter. That's all. A 'peak and tune' is by no means a complete alignment.
It has been my personal experience that every Galaxy radio I've ever checked was in dire need of a full alignment. They
will work quite well after that; so long as the radio has a chance to warm up for 30 minutes in a warm room before you use it.
Truth: I bought a new TR-696FD-1 from Sparky's CB a couple of years ago with a 'peak and tune'. When I got my own alignment tools a year later and checked the alignment of that radio, it was waaay out. Works just fine after the alignment ('4040'/Scott told me it sounded loud and very clean/clear on air). A 'full alignment' and a 'peak and tune' are two different animals. Now you know.
If this Galaxy 959 radio is operated in a cold room or car; forget about it.
Drifts like a boat . . .