We run a fleet of twelve 36v Toyota model 7fbeu20 forklifts. I've been having a problem diagnosing an issue we have been dealing with off and on for quite a while now on one of our machines. The hydraulics seem to kick off intermittently. Not 100% entirely off, but an extremely slow creep. When the machine exhibits this problem it is noticeable when you first actuate the lever. In other words, if you pull the lever and it starts moving normally right away, it won't kick out midway through the function. Sometimes it creeps for a few seconds and then kicks in normally, but when it's really misbehaving the hydraulics will just creep the entire time the lever is actuated. This is true with all material handling functions, but steering has never been effected.
Something interesting that I have noticed is that when the hydraulics are creeping along you can quickly tap on the brake and they will kick right in every single time. Same thing if you quickly throw it in neutral, the hydraulics will kick right on.
I'm an in-house guy that does mostly PM work, but we've had our local dealer bring two different techs in to try to diagnose this. Neither one was able to come up with an answer. The material handling AC driver was swapped with a different machine with no change. I swapped the hydraulic pump with another unit thinking it may be an issue with the encoder bearing on the pump motor, no luck there, either. Anyone have any ideas?

Chuck