The rapping sound is most generally a vein that is damaged and only slides part way out and the rap is the vein slamming the housing at the pint that the vein is able to protrude out of the rotor to. This is very easy to detect in the housing by a wavy at a point in the housing. Usually you will find 2 or as many as four of these waves at different points on the housing since generally all veins don't have the same point of damage.

Last night the issue with the 73 was discovered tobe the rotor is spinning on the shaft. Relatively easy weld job and possible will need to dress the housing.

We never got our guzzler to work a ladder we tried to replace the ladder but found it was to much work bringing pump back and forth everyday so it would not freeze.

Isolation valves are the best answer to eliminate sections and locate the issue point. I need to install a lot more valves...it cost me a lot last season as I could not find a drop that detached on the back side of a tree over the brook bank. I would have capped the saddle had I known where the leak was. To much snow to safely check without a rope holder.

Just think after all your troubles you will be a master faultfinder. LOL

When at the bottom up is the only route available.

Good Luck Guys!

Ben