Joe in Tennessee wrote:

My weather station has been fully functional for many years, but the
wind direction and velocity has stopped working. I suspect one or more
of the IR diodes and/or the photo transistors have failed. I have been
unable to locate replacement parts or to cross-reference the original
part numbers.
The diodes are TIL-32 and the transistors are TIL-78.
I would appreciate any information on where I might find these parts or
where I might cross- reference them to an available substitute.
Thanks in advance to anyone who responds to this request.

go to Heathkit.com they are still there and can help you out