Simple is the operative word.

Look in a mirror, see simple.

If he can't afford to have an avionics shop repair
his transponder, then he shouldn't be sharing the airspace with me where TCAS
depends upon his properly maintaining his transponder.

Financial capability is hardly the only possible explanation for his interest in
repairing the box himself. Some people, myself included, like to do things for
themselves. Obviously, this has to be done judiciously in the aviation context
but that doesn't mean minor things can't be dealt with. The OP is trying to
find out if this is a minor thing.

You would benefit from reading a book called "Millionaire Next Door." For all
you know, the OP might be one of them.

There is also one called "All I Really Need to Know I Learned in Kindergarten."
Among its admonitions a "Don't hit people." and "Say you're sorry when
you hurt somebody."

Jeez I hate these off-topic posts. I'll stop now.