To the collective, your guidance is appreciated:

Over the last month, my Brewtus has begun to misbehave.

While pulling a shot, the pump sounds like back pressure is building (similar to the sound it makes when the blank is in). The pump's sound diminishes. Water flowing from the return tubes (back to the reservoir) diminishes in concert with the pump. At times, the pump will fluctuate between 'normal' and 'diminished' during a shot.

Thank you,

Bob