Receiving sensor led always on - follow-up

Having a problem with Craftsman opener.  It only goes down by holding down wall switch.  Both sensor led's are lit, but receiving sensor never blinks or goes off, even when blocked or moved out of alignment.  I'm sure either the sensor is bad or the logic board is bad.  Anyone know which?
Also, door can be raised and lowered easily manually, so springs and rollers are OK.

I wanted to add that with the sensor wires removed at opener, you get 24.5VDC between screws 1 and 2 and 6.3VDC between screws 2 and 3.

THanks

Follow-up:
For anyone interested, I got the new sensors installed and that seems to have fixed my problem.

From what you are describing it definitely sounds like the sensors need replaced.

Thanks Brian.

I guess I will just order new sensors.  It's the cheaper of the two anyway.

I searched the internet and found 1 incident of this happening to someone else, but they never posted back what solved their problem.