Taylor Portway LPG fire with side Powerflue not working?

Model Portway Pageant SRFF16PR
Pilot lights first time every time
Fan switches in ( pressure switch ok?)
Switch on 'low',first solenoid seems to operates Switch 'high' second solenoid seems to operates.
Have Baffled fan flue outlet, fan increases speed then shuts down (as per instructions)

Any idea who the manufacturer is of POWERFLUE
(Taylor Portway are out of business)