There weren't many 35 series tractors sold in this area, so I see very few of them. I don't know that I've ever seen one with a 24 X 12 transmission. At least not one with a problem in that area. ASSUMING you don't hear or feel anything unusual or suddenly something different in the shuttle or shuttle lever when you shift into forward ?? then I can't help but think the problem lies in the dual command portion. There are too many variants of that tractor, even in a few years of production for many of the mechanics who worked on them to know them all.
The dual command consists of two hydraulic clutch packs, one for high range, one for low. I would assume it will default to low range for inching, but what actually controls that I don't know. I suspect that might vary a bit based on transmission variant and tractor serial number, but that's only a guess. With the absence of the applicable service manual, one could study the parts lists and maybe figure out what your tractor has in that respect. I can think of a few possibilities for problems with erratic clutch engagement, but with it only affecting forward operation that would rule most of them out.
