please let us know what you learn. Mine is the same. I lubed itusing Easy-Lock with graphite but was wondering if there was a product to dump into the tank that would not harm the seals.
I's not uncommon to replace the gate valve. Four bolts hold it in place. I justreplaced my bath grey tank 1.5" valvea couple of weeks ago. The rubber seals may get hard or stuck and no longer seal well.