Hi, 2.5 year old Sarena Bay spa, a few days ago I noticed a sound that I had never heard before - one of the small circ pumps was 'humming' pretty loudly. I pulled the cover and compared it to the 'water fall' pump which is identical. One is noisy (it can be heard as a "hum" and felt vibrating) and the other is silk smooth when running. Both are secured the same and the one just started this a few days ago. With both running and placing my hand on them, difference is night and day!
Any ideas? Is there something in a pump/motor that would happen suddenly to cause this vibration and resulting low frequency hum? I had the dealer come out and they say if it's pumping water it's fine

He even called D1 Tech support and they said that if it's running it's not a warranty issue. Hard to believe that a noisy, vibrating pump isn't an issue.. but...?
Rather than buy the $200 pump and replace it myself, any suggestions? It's a Laing 909-NHSW-18, 98W, 1/20 hp.
thanks...