Hi, yes a tech came a while ago and fixed it.

It was the valve for the hydraulic pump that was broken and it was loosing oil. Changed it, added a bit more oil in the tank and all was good.

Did you figure this out? Im havi g the same issue

Alright thanks

The tank should be located by the motor and pump under the big white cover. There really is only one cover on the mast, the rest is the channels which are difficult to remove.

Thanks. Where is located that tank? I suppose I have to remove cover on the mast?

It could be possible that there is not enough hydraulic fluid in the tank to allow it to go up and it pushes air into the cylinder which will compress and lower the platform. I would send the platform to that height using the ground controls and check the level in the tank to make sure it isn't empty.
The hydraulic motor/pump will also make a different noise when it is not pumping a fluid.

I also forgot to answer your other question below:
If someone did lift over the maximum capacity I would expect the issue to happen the entire time it is lifted. They would have had to put a lot of weight on it to cause permanent damage.
If I remember correctly the weight limit is 350lbs for the operator platform and 200lbs for the shelf. The shelf would break before any damage would be done to the hydraulics.

Ok thanks

Well... what it is really doing is that it raise normally then when almost at the highest height its having really hard time to continue raising. Then after few seconds it start to automatically drop like few centimeter every few second. Like no more break and can't stay up lol

The only other thing off the top of my mind would be the manual release valve. If it is loose it will cause the lift to raise slow and lower. Make sure it is fully pushed in and not stuck open. It is located on the pump under the hydraulic motor.

Thanks will check this out.

If there is no oil/leak then what could be the cause and issue?

Also, since there is a maximum weight that the wave can lift on the plate, is it possible that someone lifted things way too heavy so that caused this behaviour?

Under the work table. It should just be able to be lifted off, there is nothing holding it in place. If you look by the mast there are 2 10mm bolts you can remove and take off the cover, this exposes the bottom of the cylinder and the hydraulic hose and fitting. If there is a leak it most likely will collect in that channel.

Whats the « cover » you have to remove?

It could be a bad seal on the lift cylinder. I would take the covers off and look under the mast to see if there is hydraulic oil there. If the oil is running down the cylinder, it possible one seal or both could be bad. Otherwise the fitting or hose could have a leak.