Quote Originally Posted by Saint-Just View Post
Both the above comments are probably correct but in this case it appears the pump is working, just not when it’s plugged where the OP wants it to be.
This says maybe there is an issue on that leg of the ring - it’s the only logical explanation
Have you retried it where you had it working

I asked about water as I thought it may not operate without a flow
Are you sure you’ve not damaged it running it without water supply?