Phono input troubleshooting on a preamplifer

I own a Harman Kardon HK 825 preamplifier that is equipped with two (2) sets of phono inputs and is easily switchable from MM to MC with a push button on the faceplate.
The unit is marked "phono 1" and "phono 2" on the faceplate and two (2) sets of gold plated input terminals are located in the rear.
I've used my Harman Kardon T60 turntable with a Grado moving magnet cartridge in "phono 1" with excellent results.
I just purchased a mint B.I.C. 981 turntable with a Shure moving magnet cartridge with the intention of using "phono 2". (The 981 works fine in my bedroom system.)
However, I've just learned that "phono 2" does not operate and I have no sound.
In fact, my further testing has revealed that my Harman Kardon T60 works when the faceplate input selector is selected to either "phono 1" or "phono 2"!
Insofar as my T60 is connected to the rear terminals marked "phono 1" (and not "phono 2") I'm at a loss to understand what's going on here.
Why is my T60 working on "phono 1" and "phono 2" when it is connected to the "phono 1" terminals in the rear?
Why doesn't my 981 work in "phono 2" when my T60 works great in "phono 1"?
Any suggestions to avoid bringing this unit in for repair?