Used part of a day of from work to start on the re-assembly of the heater today. I had hoped that I would get the heater's internals and casing back together. But sadly I should have taken even more pictures during dismantling. So I lost a fair amount of time working out how some of the parts needed re-fitting and in what sequence. But I managed to figure it out in the end, partly thanks to a spare heater unit I temporarily stored in the garage for exactly that purpose! But despite a few setbacks, at the end of the day the most difficult parts were back together;
Only two flaps, the ventilator & motor and the upper casing cover remaining. After which it will be time to get all the activating rods back to where they belong.
And during the assembly work I found an easy way to fit the retaining rings for the flaps and rods. Thanks to my trusty small ¼" socket set. Support the opposite side and simply press the rings on. At least one job that was far easier than the disassembly phase;