On Monday, February 25, 2019 at 6:29:48 PM UTC-5, wrote:

Hi Mike,

Yes, the problem seems to have been fixed long term. The pins in question on
IC503 where I installed the 100k resistors to ground were the noninverting
pins, #3 and #5.

Good luck.
--
David Farber
Los Osos, CA

Hi David. I know this thread is a bit old. How do you solder the 100k resistor to noninverting pins #3 and #5? Do you happen to have a picture of the actual solder of the resistor? Also on the resistor, what watt is the resistor? Thanks!

The wattage is unimportant. If you're using leaded resistors, use 1/8 watt and go from pins 3 and 5 to the nearest ground (like pin 4). What I would do is use a couple of smd resistors and tack them from pins 3 and 5 to pin 4 ground.

Did anyone try actually replacing those op-amps?