Well not to be contrary with you as I may never get some of your formulas and excellent advice again , BUT
I humbly reply that I would never run film through a roller transport machine and expect scratch free film.
In fact we will refuse to print for photographers on condensor enlargers or will invoke a retouch fee for those pushing film through roller transport.
In the last 20 years printing for others, I cringe when I get film that has been run through these machines for large prints and today I usually turn the work away or at least give absolutely no doubt in the clients mind that the scratches are not my responsiblity and they need to find a good hand retoucher to fix the problems.
And if the UK Pro Labs are using this equipment for UK photographers then shame on them .
Only in Canada you say.
Originally Posted by Ian Grant