Another "stitch in time" there Steve and an impending ECU & carpets disaster avoided.
(Jules tip here on removing the Poppet oval clips. No need to dig them out with a screw driver, which can leave unsightly marks on the skuttle panel, instead simply put your fingers over the clips with one hand while giving the panel a sharp tug, The clips pop out of their own accord)
Advice to all:
Make sure the end of your tubes are circumcised!!
It does help stop them getting blocked as long as you stop the debris entering the plenum area in the first place
(either use DIY gauze or order my Plenum shield kit
So many Garages remove the lower plenum tubes ans it's a silly thing to do IMO.
Water then gets into the box section to cause further future problems.
Plus we bought the last few remaining tubes from Rimmers.
Maybe replace your missing tubes from salvage cars .