[Mr Gazza]

This is a common fault unfortunately. I regard those connectors as a routine service inspection item.
Bad connections there cause high resistance in the cables and rectifier and I believe that is cause of many rectifier failures and fires.

Make the best connections that you can. Some folk hard wire, others use crimps to join the cables (not crimp on bullets, but a crimp to join the cables.)
I use Gold connecters, as available from model shops, as used on electric models. (Use no less than 4mm)

Once you have a low resistance connection make sure it's weather proof... Heat shrink is good, but what ever it takes to work.

Check connections for security and corrosion once a year.

Post Script.. By the way those do not look like original connectors and I don't think the brown cables are original either, they would have been yellow cables.
I think the original was a white plastic block connector.