We can close this one off guys. I fixed the problem today!
After almost throwing in the towel and letting the local pro take a look, I checked the Pump 1 power to the board and noticed that the black wire was slightly pulled out of the plastic housing and thus not making contact. Re-set the wire into the housing, and voila - low speed is working just fine.
Thanks for the assistance @RDspaguy @CanadianSpaTech