Hi
Your issue could be cause by the following
The silicon strips carbon contacts could have gotten corroded on the microscopic level so you may need to get some very high grit sand paper and carefully take the top layer off(not much though)
The carbon contacts will on the board could need the same treatment as above or could need the opposite….More carbon contact….if that’s the case ,if you carefully get a pencil (writing pencil with carbon/graphite in it)and draw on top of the contacts you might be able to breath some new life into them
All in all it sounds like the issue is that the contacts is poor…the reason why it’s quiet is because of the keyboards “velocity keys”
Velocity keys is where the keyboard usually uses 2 sets of contacts and measures the time taken for them both to make contact with the strip(one constant is a couple milliseconds behind the other) this is so it can tell how hard you are pressing down on a key (hard or gentle)
Hopefully this helps
Any questions please ask
Thanks:-)