I grabbed my T1 today, planning to throw a wire up into the tree and make a few Field Day contacts..... it was dead, and no it wasn't the battery.
I opened it up and found no 6 volt output from the U2 regulator when I pushed the TUNE button. Tracing back I found that I would have 9.3 volts on the anode of D3 (1N5817) and about 8.7 on the cathode, but when TUNE was pushed, D3's cathode went to 0.5 (referenced to ground) so nothing through Q1 and so nothing on the input of U2 regulator, and so no 6v. Just to verify this I grabbed some clip jumpers and put a 1N4007 diode in parallel with D3 and I got my 6 volts back.
So a couple of questions here. Last fall when I checked, the T1 was working fine.... What the heck killed D3? And... I don't have any 1N5817's in the part box, but I do have the general purpose 1N4007's. The 5817 is a Schottky diode and I assume it was chosen for a specific reason (low voltage drop?) but can I substitute one of my diodes here or is it time to place a parts order?