Hi too bad for the screw... you need to replace some mosfet ? I thought it was all good ?
my first source for me is Digi-Key and mouser. But often, old part are discontinued. In this case I try ebay. But problem with eBay you are never sure what quality you will have. Good, doa, fake...
Another thing you can do is find a replacement equivalent mosfet. Active and in stock.
Now, 9627 9727 is not important. It's just a date code or something. The part number are tip36C and tip35C. You can also found this info in datasheet. Q1 to Q8
For your switch it's normal, you bypass r184 r185, it's always power on.
Try to resolder everything. replace c105 and see what happen.