9 pin connector - dash cluster - 69 'Cuda

Made a bit of progress.
Verified wire is good from sender to 9 pin circular connector.
Verified gauge worked by applying 0 - 5VDC and got 100% gauge deflection.
Removed sender from block and it ready steady 24 ohms despite applying up to 40 psi compressed air.
I have an old sender and it goes from ~ 80 ohms to 36 ohms when i apply up to 40 psi compressed air.

Looks like I need a sender.
Oh well, I'll take this opportunity to clean the inside of the gauge bezels and refresh the needles.

Now if I could only figure out how to remove the trip gauge reset knob.
Is it as simple as just pulling it off and re-gluing later???
I'll take a closer look.

Thanks for the help.