Both these radio's are fine performers. They both suffer from the PLL trimmer cap issue, and the 761/751A has a 100uf cap for the 8v regulator that tends to dry out, I suggest a 35v type for it's replacement.

Here is the 761/751A PLL Alignment info. 751A/761/765 PLL Alignment

Both radio's have a somewhat rare issue with cracked solder in the DP6(A) DC/DC converter unit on the Display Driver unit. The symptom for this is "no Display", or the the display blinks as you rotate the tunning knob.

The other question I get fairly often is for the 765 tunner alignment. Here is the 765 info. Alignment sheet and Board Layout The alignment sheet refers to R104 ect.., this is R4 ect..

Tuner relay attenuating Rx seems to becoming more common these days. The 765 does have a pulse clean circuit for the relay, it is activated for about 500ms each time you turn the radio on (main power switch) if the radio is left on, the pulse circuit can't do it's job, as the the circuit only fires up, during power on. Cycling power will do the same as the next procedure, but is a little harsh to the internal supply.

To electrically clean the tuner relay, unplug the RANT in rca jack. Next connect a 9v battery (or other low voltage, low current source) to the main (SO239) antenna connector. Turn the 765 on, using the main power switch. Briefly touch the center pin of the RANT in Rca jack to the chassis (half second), you can repeat the process several times if desired. Remove the 9v battery, and reconnect the RANT in. RX should work normal at this point, if the relay was at fault.