muffled reed in Instrument Construction & Repair Posted August 26 · Edited August 26 by RogerT I would check the valves. I keep encountering the following problem: someone has cleaned and revalved a concertina (and an unsuspecting buyer has got hold of it in a 'restored' condition) but fixed valves that are too thick and or has glued too much of them so the valve is restricted…but they obviously never checked the result of their work. And the smallest tweak can alter the behaviour of the reed, taking it from dull to bright. Sometimes just flexing the valve up and down/back and forth can fix the issue. Or I replace the valve, taking care just to glue the very end of it and not half of it. Leather accordion valves work ok..the funny shape is just so they fit in the tapered chamber. If you have a way to get the reed pan out and lay it flat on some tuning bellows, block the chamber end and you can then observe the reed working and play around with the valve. The other problem is that the cleaned reed (all lovely and shiny) hasn't been 'voiced'…in other words the gap has been set correctly, or of the reed has been distorted by cleaning, the shape and set haven't been optimised. Or the reed is loose in it's slot. All of these things can be dealt with on the tuning bellows. If it sounds good on the tuning bellows but dull in the instrument, then it's an air issue…the pan isn't sitting flat against the action box or some other problem.