[Amps] HF-2500 T/R problem

[Bob K6UJ]

I have the older version of the Commander HF-2500.
When I try to key it up, it will click on for just a bit, enough for just one dah, full output though, and then click off.
I tried  unplugging the PTT cable and shorting across it for a test and sure enough it will key up for an instant then click off.
Before I open her up I wanted to ask if any ideas from the group, particularly someone with a HF-2500 for ideas.

tnx
Bob
k6UJ