our more popular P203 units have a threaded top on them for maintenance purposes, however, for reservoir removal, most are threaded on to an adapter on the body or it's a quarter turn counter clockwise. We offer special tools for their removal but a strap wrench at the base of the reservoir will work as well. ~John
The P203 and P653 don’t dispense very much lubricant or build much pressure under normal operation. Worst case could be a worn out pumping element. ~ John
