Where did you get the 122.9 belt?
I got the part number (B120 - Product# 90032120) from the Gates website. There is an auto parts store nearby that carries Gates belts, so I had them special order it for me. I had to pay a few bucks more than NH, but wanted to see if it actually measured to spec' - it does (122 7/8").
I have communicated with the TBN "Messick's" member. He was very helpful, and refered me to their "tech guy". I spoke to him yesterday, and he didn't recall hearing about any issues with the belts, but was going to check, and get back to me today. I'm also going to ask him if he knows what prompted the spindle re-design.
I'm also really curious about "Haymaker's" mower. NH doesn't show the 930B in their product listing anymore, and I'm wondering whether they're bringing one in from another dealer, or if he's actually getting another model. I guess we'll have to wait and see.