The issue with the VR642 equipment seems to be related to the hydraulic pump. The user suspects that the pump is getting weak after the equipment runs for about 10-15 minutes or when the transmission gets warm, causing it to slip and not pull properly. Despite having clean and full fluid with new filters, the problem persists. This situation suggests a potential problem with the hydraulic pump's performance, possibly due to reduced efficiency or wear over time, leading to inadequate fluid pressure delivery. The user's assessment aligns with common symptoms of a failing hydraulic pump, which can result in reduced functionality and performance of the equipment.