Cheers everyone. Great stuff.
If I bin em they yours for free but going to give em a try for a while.
Cut up the wife's chopping board and got the Heath Robinson manual out and cobbled together a plate to raise the mounting plate and push it backwards. Looks crap but sort of works but still hitting horn.
So going to buy a 20mm piece of polypropylene or nylon and try it in one block. Need another inch I think. Mind you may end up with the bag in me lap.