Clearing airlock from multiple pumped showers

[GerryB]

I have a negative head twin impeller Stuart Turner pump feeding hot and cold to three showers, one bath, plus hot to three basin's from my gravity fed, loft cold water tank and airing cupboard hot water tank.
Occasionally the pump operates for a couple of seconds without demand for water. More often 10 to 15 minutes after a shower has been used but very occasionally at other times, perhaps in the middle of the night. It's no great issue but something I would like to fix if possible.
There are no signs of any leaks so I think its more likely an airlock. There are long pipe runs (maybe 12 to 15 metres) up through the loft plus pipes that run under the floor to the bathrooms and en-suites.
I have seen instructions to remove the airlock by removing the shower head, leave the pipe dangling down, switching off the pump and running cold then hot for 5 minutes, but I've not seen instructions for multi outlets from the one pump.
Should I do each outlet in turn or all at once?
Does the fact that each shower has a rainfall as well as a handheld make any difference to the process, i.e. do I need to remove the rainfall heads as well?
Thanks in advance for your expertise.

 

[ShaunCorbs]

It’s not an air lock I suspect the pressure transducer is starting to fail as a neg head pump works on pressure so it’s monitoring the outlet pressure or you have a slight leak

 

[John.g]

These pumps have a little air pressure vessel like a mini exp.vessel and should be checked/pumped up via a schrader valve (air side) to something like 0.7bar with both hot and cold outlets depressurized and slackened off.
Edit.