I bought it knowing full well it had no drive and didnt run that well, but I paid a suitably low price for a forklift with various issues & yes, It was a damn good clean out of the sump to remove the debris, a valve stuck, clean correct grade of oil and new transmission filter. I was thinking round what the issue was then I got the gauges on the test ports and went through the book and things pointed to oil flow issues as there was too low pressure on a few tests. I had the valve block off the top and stripped and cleaned it and the relief valves out also looking for the issue.
There's a hyster group on facebook I was in at the time and some of the people in there were hyster techs and really clued up & that's where I was told about the grade of oil being really important. And I hunted down the complete manual set for my exact machine which was a mine of information.
I didn't have to do the clutch packs, at one point I was thinking they or the pump were the fault and started pricing the job up & for my specific model the plates are not that expensive themselves to buy and it depends if you just need frictions or steels too, if the pumps ok or saveable or needs a new one etc. I think the worst of the job is taking the transmission out and splitting it to get to the clutch or pump as there's various schools of thought on what has to come off first to do this with some people saying mast/front axle, some saying engine out then work on it from inside the space cleared, but either way it sounds a pig to get to, so you would want to renew both while you were in there and use new seals so a few hundred euro on parts alone for sure. And the torque converter itself seems to be really expensive if it needs one although you might find somewhere that can recon it or get lucky and drop on one on ebay and import it.
When the machine is lifting something near its capacity up the ramp to my workshop I do have to gun it a bit but its steeper than the max recommended angle for a ramp in the hyster manual after we screwed up a calculation building the workshop ramp shutters. On the flat or gentler inclines its fine. I have used it to wheel around my machining centre at 4t picking up one side with the other sitting on skates no issues so its fair to say it has plenty of drive.
I found these guys great for parts but their website was terrible and they reckon its undergoing overhaul when I pointed out some issues, but they may have fixed them by now. I'll ring them up for parts and order over the phone if I need more stuff though.
https://www.lsforklifts.com/c78593/tran ... discs.html