Check where the dust goes into the machine, there's a flap there that gets stuck (pulsing means the machine has found a fault, then reboots to see if the fault has gone)

I've had faults with the head cause issues like this, does it still do it with just the machine and no extension tube/attachments?

Hello,
I seem to have a very strange fault with this cleaner.
The cleaner started pulsing so the pre filter was cleaned.
A few weeks later the battery died and was replaced,
on reassembly it started pulsing again.
This time the unit was stripped down and the cyclone
was found to be filthy and was thoroughly cleaned.
the pre filter was renewed and the motor filter cleaned.
after careful reassembly the problem persists!
the cleaner will work/run if you lift up / remove
the round pre filter,as soon as you  let it go
the suction seals it and the motor pulses again.
I cannot understand how/why the filter is
stifling the airflow?
I am tempted to drill several holes in the
top of the filter body to let the air into
the cleaner.
I have tried removing the filter fabric and
putting just the filter body back but
that does not  work either.

Any thoughts please
 

 that was my thinking.

thank you

I still prefer to buy such things new, and they should be of high quality. Also, I usually call the cleaning service monthly to clean the entire apartment.

It's most likely one of the PCBs at fault here, probably the top one.

It's hard to be completely sure without testing it in this case.