P38 Replace heater matrix - stuck!

Replacing my leaky heater matrix with a Nissens Audi one, but am (literally) stuck removing the old matrix.
Not wishing to take out the dash, I have cut away the supporting frame as per PaulP38's instructions.
All looks OK to slide out the old matrix, but it only comes out about 1 cm then stops.
Looks like it is just fouling the Valeo unit above it.
Or is there some other catch or clip etc?
As ever, advice gratefully received...

Never done it so dont belive me .

Looks like you need to slack the screw in the valeo unit or release it totally. to give you that little extra space.

J

Take that blend motor off, its only 2 screws and it pulls off. The drive is D shaped so you can't put it back wrong. However, don't turn on the ign until it's refitted.