Just to be sure, this is the meausurements into the R/R itself, right?
The diode readings should be ~ 0.6V forward and 0 reverse.
The diode setting sometime doubles as the 'beep' mode, but there is perhaps another switch to differentiate between them?
(Do you have link to the model of your meter?)
You might try the resistance on 2k range,
But fact that you have no shorts - and that all the diode juntions are all consistent with each forward & reverse is a good sign.
It's not really looking like much wrong with the R/R.
Check your ground connection to the motor and also the battery terminals are secure & in good order.
