Tycos palm sphygmomanometer VALVE not working after degreasing it

My Tycos wasn’t used for many years and initially during deflating the needle was sort of bouncing.  I sprayed a degrease (CRC) in the valve and started working fine.  I thought that sticky black grease needed to be replaced so I sprayed more CRC until the whole was clean.

Unfortunately any grease that I added, including the super sticky PG-44A, did not revive the Tycos.  The valve act as an ON-OFF switch and it either closes completely when the screw is all in or opens completely at the minimal turn to unscrew it.  I cannot remove the valve, the nut seems to be glued to the chassis.  Tycos is a very expensive brand (over $450) and would like to repair it.  Any ideas?  Thank you.