Low A is slow and flat [English]

[DaveM]

The low A on my brass reeded Lachenal, English, is slow to speak and quite out of tune.  Only the the pull (expanding bellows).  The other A1 reed seems fine.  I opened up the end, on inspection I didn't see any dirt or debris, nor any sign of a crack; cleaned the reed anyway.  Nothing was obviously wrong with the valve, plus I wouldn't expect that to affect the tuning.  This has been going on for several months now.  Not sure what to do.

[Mike Acott]

It is odds on the reed tongue is cracked and will need replacing , I have no doubt others will concur with my statement.I wish you well with the repair.

Mike

[Chris Ghent]

If it is cracked you may be able to confirm this by measuring its tune and then pull on the bellows really hard while watching the tuner. If it flattens and then doesn’t come back up then it will confirm Mike’s diagnosis.

[david robertson]

A more radical diagnostic procedure is simply to bend the reed upward. If it's cracked, it will simply break along the line of the crack.