reading through various posts a typical comment is like

"and most problems are related to poor connector connections or dirty contact pads on the boards (from my experience)."

are these connect issues plugs comming off wires?
what do you clean "dirty contact pads on the boards" with?

It depends on how bad they are.
If they are only a bit tarnished then a normal white pencil eraser works great.
If they have corrosion they might need some light wet & dry sandpaper and if you remove the silver plating, then re-tin them with solder, also if the contact on the boards are corroded, then the connectors will need to be re-pinned as they will also be corroded.
If the connector pins are just dusty and dirty, you can use some thick card and windex to clean them.