On all later models I used a much simpler ‘Cliff’ type XLR connector that was secured with self-tap screws the same as the ends.
On the funny noise….. I don’t think it’s significant as long as it works OK with the power on. It could indicate that there is a ground loop in your system , but if it’s working OK don’t worry! No, avoid replacing caps unless it’s really necessary. It’s usually a waste of time and effort.