I don't know the answer Mark but somehow while restoring and loads of buses I still don't have one. Got that one on somehow!
I have no doubt of your abilities Steve. My suggestion of a box spanner (6mm) was for the chap who started this thread. It's so much easier with the right tool, I'm sure you'll agree
All done , it took two seconds to remove the 47 year old piece of tubing, but an hour of fu*king around to get the new piece of hose in, cutting the hose to the same size as the old piece helps. Using washing up liquid on the two pipes was a good idea, helps to get the hose onto the pipe end that heads towards the tank first and then aligned to the fixed end that heads towards the air vent. I had many failed attempts before it slipped in nicely! Hopefully no more petroleum smells. The others at the tank end have been replaced bar one which is a bit annoying, but it looks in good condition .
