Kenwood TS-790A S-Meter issue

[Crambone]

I have a TS-790A and the S-Meter isn’t working in ALC or RF position on 144MHz during TX, it does show signal on RX. It also works on 430MHz both TX and RX with no issues.
I’m hoping someone can point me in a direction or explain the path the S-Meter takes on the 144MHz.

I do have full power output on a bird meter on 144MHz just no S-Meter movement?

Here is a link to the Service Manual.
https://www.ko4bb.com/manuals/104.28.55.227/Kenwood_TS-790.pdf

Any help would greatly be appreciated.
Andrew

[Crambone]

Anyone?