Before you purchase a turn directional relay, how does the turn directional switch feel ?
Does it have a detent, or does it feel limp / non distinct when using it ?
Not uncommon to have the switch plastic parts come apart with age and cause the turn directionals to not work or to stay on .
No, the relay will not have an audible sound, that was only on the first generation R65's, '78-'80 and that required additional wiring and the 'buzzer' as well .
The part from Motobins is the correct relay .
The diode for the neutral indication problem, is located inside the starter relay, not outside in the harness (as the first generations bikes have ), or another component .
As far as cleaning the switches, they are not real user friendly to disassemble, a bit of small parts with springs and small steel ball type parts and again the possibility of the plastic bits in there being in bad shape, there are no individual parts available for them, you need to replace the entire assembly .