I have 4 uBITX radios and the first one had stuck the left side relay early on. I replaced it with a stock component and it has worked fine. None of the other machines has had a problem. This relay only carries signals on the receive side so no chance of spurious emissions.
Good luck with your repair.
I approach repairs from the viewpoint of a repair technician rather than that of an engineer. I always get a chuckle with those who think they need a wall full of test equipment to fix these critters So far I have been able to resurrect all 3 uBITX radios determined to be junk by previous owners.