So, looked over the service and owners manuals on the phone.
Units sold in the US or Europe don't come with the voltage selector switch.
Can't find a single bulb listed on the service parts.
Page 41, section 9 of the owners manual is interesting in regards to the tape counter. Says the tape is measured mechanically thru tape movement, and will vary from standard elapse time based on the type of tape used. That's why you press a C-46 or C-60 button to calibrate the counter for the type of tape used.
And then, in sections before this, they talk about the memory functions and multiple button presses and how the tape counter resets or doesn't reset, and where the tape starts or repeats and so on.
Oh, and I could find no calibration for the counter.
So, it's a very complicated, logic controlled system. Yet the counter seems rather crude if it somehow measures the tape mechanically, so it's probably not dead on accurate, just my guess.
Best I can say is run through the owners manual step by step, making sure all the memory functions work. Then start playing tapes normally making sure you set the counter to zero and tape length correctly. It may be working, as designed, just not as well as you'd like.
But, I have only one tape player, in my old car. Never even tried it as I have no tape. Hopefully the other guys will help. Please!