Jobo ATL-2300 chemical pumping error

I have recently acquired and plumbed in the ATL-2300 and am getting an
intermittent error, occasionally a this doesn't occur, but more often
than not at least one of the 3 baths of E6 chemicals are not pumped
across into the drum. I am using the front bank of tanks and tanks 1-3.

The machine makes a bleeping sound, by pressing "Start" it then pumps
the chemicals across with no difficulty whatsoever. This problem is
causing streaking on some sheets of film (mostly doing 5x4 E6) and
clearly isn't operating as an Auto machine as I have to be on standby
to go and press the button!

I have checked seals on lids of chemical bottles, smeared thick
Silicone grease around the top of the o-rings on the bottle, replaced
the red seal on each of the tank lids, but still the problem recurs.

FWIW I have tried Autofill options and where I set the chemical volume
manually. This seems to have no effect on the problem.

Those that have experience of these machines please could you advise on
what I should be checking to rectify the problem?

Prior to this I have been using an ATL-1000 which has been fine with
the tanks I am using now.