Problem is no one makes the power transistor these boxes used to use, so they got redesigned to use something still being made, poorly redesigned that is.
I did some research into this a while back, there is (was?) a similar power transistor that could have been used, but it was more expensive. IIRC and it was a couple of years ago when I did the research, that transistor was something like $30 each from Mouser.
Do you know what the part number was for the replacement? I have connections for obsolete components and may be able to find them
