GPO 328 - low receiver volume

[Chris328]

Hi everyone,

I recently bought a GPO 328 from ebay and it's fine in most areas, but the earpiece volume is very low. I'm wondering if there's a simple way of checking for faults that might cause this (I'm not very experienced with old phones, although I can follow a simple wiring diagram, if it comes down to which colour wire goes where).

Or perhaps some sort of conversion that's easy to fit and will solve the problem?

cheers
Chris

PS: attached is an image of how things look (the receiver is wired as per the original diagram (white to mouthpiece))