I have split this into two posts so please read the previous one as well.

To answer a couple of your questions.

Wire jumpers on the power supply - the circuit board is single layer, it has copper tracks on one side only. Connecting certain points together is impossible using the tracks on the board because you need to get over/around other tracks. They are sometimes referred to as wire bridges which is perhaps a better a better name. More complex circuit boards a double layer or double sided with tracks on both sides which effectively use tracks on one side to jump or bridge tracks on the other side. Then there are multi-layer boards which have copper layers inside the board.

Difficulty reading the marking on devices - in more recent times manufacturers have changed to laser marking to put printed details on devices. I am not keen on this as it is sometimes very difficult to read. Previously they used to use ink marking which was much clearer but who is said progress was supposed to be an improvement?

I have looked as some other power supplies and would suggest that PC41 and PC91 are PC-17L1. I would expect just about any opto-isolator to work but you need be careful as they come in different packages, some have 4 pins like ours but others have 6 or 8 leads.