Tape will not load

A schematic would definitely be a plus here, as you could then check the logic levels from the sensor(s), as the "light path" is interupted. If voltage levels changed properly, and no tape load was initiated, then this would indicate a problem elsewhere.

You may want to also check for the presence of power supply voltages. If the voltage supply for the loading motor (often the capstan motor) is missing then there would be no load initiate.

It sounds like you have some knowledge of how these things work- a good thing.

As you are probably aware, todays electronic equipment (VCRs included) is substandard, disposable, not worth investing much if any repair. Find an old Panasonic manufactured unit, and such will often outlive several of these "lighter than air" cheap rascals.