I am upset by Yanmar's assertion that if I advertise a tractor I lawfully acquired that I am violating their trademark. A company making that claim, whether to someone else, or to me, is evil, wrong, and unjust, irrespective of whether I am the target or not. I think it is important to discuss the core issue, and, as mentioned before, it is this: Yanmar is claiming that they retain control over who is allowed to sell their products, whether they can be advertised, and whether or not it is legal to buy or sell parts for machines they made.
There are numerous other ancillary things that get roped into this discussion, like the quality of refurbished units, personal responsibility, and so forth. At its heart, though, the question is this: If I buy a tractor (or pair of shoes, a car, kitchen knives, watches, etc), is it legal for me to later sell it, or should the original manufacturer be able to sue me and take it, with no compensation to me? This is the crux of the issue, and the fundamental question.