DJ, I do things rather crudely because I am too cheap to buy the proper tools. I take two tiny bits of duct tape and fold them each over a couple of times with sticky side out. Then I place each on the logo ring surrounding the front element, about 180 degrees apart. I then take a pointed pair of scissors and position each end on each piece of the duct tape. Then, carefully, I turn the ring counterclockwise to get it started and getting it loose. After that I can usually turn by hand, but there are annoying occasions where the filter ring is dented and the logo ring will not screw off so easily. In those instances I must use pliers to straighten the filter ring and even then sometimes I end up having to drill two tiny holes into the ring, again 180 degrees apart, and force off the ring with the scissors. Not fun.
Depending upon the lens, after the logo ring is off there might be screws holding the filter ring which have to be removed. Or there might be another 'spanner ring' to remove by the same pointed scissors. I forget the exact way the Mamiya lens is put together but I do know that it is easy to do. Unfortunately you are about 3000 miles away but maybe an Olympic discus thrower can aim from London to Philadelphia and accurately target my waiting hand.
Sorry for the delay with my response but I do not have a computer at home. - David Lyga
NOTA BENE: Craig, doesn't the turn have to be COUNTERclockwise? I have never met a filter ring that turned other than normally. Sorry, you prefaced the clockwise with 'anti' so you are technically correct, but, perhaps, 'counterclockwise' is a bit more intuitive.