Unitrol TMD siren PA not working

[Safetyman]

I was given a Unitrol TMD siren in great shape. Pulled from a Vol chiefs car working except for the PA feature apparently. Siren and Horn modes work. I have tried 2 mics (MNCT- SB) both were used no luck. When selector is set to PA, pushing the ptt button makes 1 relay close/open but no audio from speaker. The TMD is a nice unit and a great add to my collection.
Any insight on what may be the problem?
Appreciate the help,
Safetyman

 

[shues]

The troubleshooting instructions in the Touchmaster Delta manual are as follows:

 

[Safetyman]

Thanks for reply. Looks like it's heading to Kents Siren repair shop.