[Melodica-Me]

Hello Dean, you have a cracked reed. not visible to the naked eye, but those are the all signs. EBay has them, this is for the 44H if you have the HP the same seller has them.

Melodica-Me

https://www.ebay.com/itm/New-Hammond-Pro-44H-Melodica-Replacement-Reed-Plates-MP-252-/152721377966?epid=2255298728&hash=item238ee74aae:g:yNIAAOSwE0JY8k67