strange phenomenon

Hi All,
I have an occasional extremely low volume issue with one channel in my phono chain. Some days it plays as it should, the next day I have one channel sound and the next day all is good again. Cart is at33ptg/ii on a vpi traveler and a heed quasar, the amp is a peach tree decco 65. I have tried swapping cables ect. and cannot seem to find the culprit, it simply does it's own thing. thanks for the helpful advice if you have some.

A wire in the cartridge may not be secure. Ditto any wire in the chain.

(I would suspect #1 likely to be: the tonearm wires. A broken wire but still touching itself internally in the arm)

A loose solder joint, can also be the culprit.
The only way to find the problem is to substitute other items for what you are using. Different cables, And if you had another phono section that would be good to try.
Otherwise it may be impossible to locate.
Agree with Elizabeth's suggestions. Had a similar issue and it turned out to be a bad contact in the cartridge. Do you by any chance have another cartridge you can substitute in? (BTW another Heed Quasar owner here).
Agree with Elizabeth, but before you commence diagnostic swapping, check that the tonearm wire clips are fit snugly to the cartridge pins.
Thanks folks, I checked the cartridge connections, all good. I'll swap the cartridge next. I'm hoping that the ptg/ii isn't defective. if it is, balz ! it's only time and money.

thanks again
Not clear. Do you have NO sound from one channel, intermittently, or low volume in one channel compared to the other? Thanks. If there is signal in the intermittently defective channel, then the diagnostic possibilities expand.
... the diagnostic possibilities expand

How delightfully dry.
swapped the cartridge, problem solved. i really do appreciate the input