Hi there Simon,
no, although the 3 long bits of foam go behind the front panel, I think the square of foam came from within the motor compartment - the exhaust grille was originally covered with a thin grey foam sheet, same as the exhaust grille of the Portapower, or the foam filter-block inside a Constellation. However, this has almost totally disintegrated, so I tore the rest of it out when I was younger, as bits kept flying off in the airstream!
Thinking about it, I'm really not sure where it goes...I'm just sure it wasn't behind the outlet grille! The foam rubber does seem to be in good condition, in fact I think I washed all the foam bits when I first dismantled the machine, to get rid of any old dust/carbon residue etc...I don't think it can have been used all that much, it has some scratching to the chassis, but nothing serious, and it doesn't suffer from any wobbly-handle syndrome, which I hear these cleaners are prone to. I'll relate all I know of it's prior history below...
The motor mount bracket I mean is the one inside the motor compartment, on the right-hand side, which holds the motor in place by clamping the round rubber bit which goes over the middle of the fan-end (if all that makes sense!). I've found two screws which seem to fit ok (although one seems a little too long, and won't screw totally down), but this means I'll be missing two from somewhere else! I may have to continue to assemble the cleaner until I find where screws are lacking!
Getting back to it's prior history, I got the Convertible, along with about 10 other cleaners, from my Design Technology teacher, who had all of the cleaners in the DT rooms for product analysis. When he got a grant to have the workshops redone, he offered them to me, since he had no room for them. His only condition was that I took them all, I couldn't pick and choose, and they had to be gone by the time he got in the next morning!
Unfortunately, he didn't want to part with the mint Goblin Wizard he had, which for quite a while was suspended from the ceiling above his desk in his office. I did get the Convertible though, and an early Premiere Junior, as well as several 1224/119-type cleaners, and a few Lux 500/Twin Turbo machines. I kept all the ones I liked, and a few of the others went to the dump...this was long before eBay/discovery of other collectors, etc.
The Convertible itself narrowly missed being skipped a few years back when my parents made me get rid of all but the oldest of my cleaners. My mum hated it, because of it's "ugly" colour scheme, but I didn't give in - and this was before I knew anything about it's rarity over here. I just remembered seeing it in an old 'Which?' report my granny had given me, and since I'd never seen another one, I thought I'd keep hold of it. I'd never forgive myself now if I had thrown it away back then!
A picture of it back when it was whole:
