I remember a 15-16 years back, there was a gutter firm we used for the same situation - He had a backer for the K section of the gutter - 4 solid steel shaped bearings 2 on either side, the runner - flat steel bearing (same dimension as the runner) and 1 steel bearing on the center of the facial section and he could regulate the arch - it was amazing piece of equipment-Copper ,,,of coarse . Check your local gutter distributors, they may have some attachment as part of their offered services- ask around, you never know, and good luck!
try this company
http://www.ornametals.com/products/c...?cPath=100_150