help identify the part number from the marking of SOT-23 components
You could desolder each, one-by-one, and run them through a good tester to uncover what type of device they are and their pinouts. Some testers even report beta, handle mosfets, etc. Even with this knowledge you'll still have to reverse the circuitry to find modern devices which suit it.

To get the conformal coating off, Pace has a helpful video.