The resistors are 0603 which are usually a max Pd of 125mW, and the opamps have somewhere around 70mA of drive current. And 0.07^2 * 47 ohm = 230 mW. So, there are probably a fault few conditions you can get into where the resistors might open up. That’s what they are there for. The QA402/QA403 went to 100 ohms on the output, which lessens the concerns considerably. But then you have higher output Z which can have its own drawbacks too (especially for driving transformers).
One the lid is off, with the circuit unpowered, check each R using a DVM and report back what you see.