You're in for a somewhat large project there. The connector is for an electronic coin mechanism.

Odds are, if the electronic mechanism was fitted, there may be mounting hardware for the mechanical mechs missing.

The wires from that harness may need to be moved to the coin switches below. I also notice a lamp socket is missing in your coin door.

The easiest solution would be, IMO, to find an identical door wired for mechanical switches, set the two side by side, and remove the extra wiring, and reterminate the wires that are needed for the coin switches.

I like a challenge, so I'd rewire it properly.. but most would just replace it.

Yeah I am going to rewire it.  The rewire is no problem for me - handy with a soldering iron and used to do XBOX 1 chip installs - so shouldn't be too much of a hassle now I know what I am looking at.  I have a spare lamp socket here - so will just get some connectors.

I have a 20c coin mech already - but might get a $2 and $1 one that will bring it up to what I want for it.  It is only home use - however I wouldn't mind using it as a big piggy bank to pay for the next one.