There isn't a cylinder leak because the oil puddle would be there, not over in the tank area (these two areas are separated). Please note, this is happening on three machines, so it's a design flaw or a service technician mistake before me. Older model WAV50-118 would start to leak on the lowering valve solenoid, but that's after 15 years. This seems not to be the case on this three machines. I've also taken out the hydraulic unit from the tank, changed the o-ring and that also didn't change anything.

I've only notice that the sponge in the tank cap is completely soaked and the top of the tank is wet. So I'm thinking that there is a lot of hydraulic oil mist which drips from the cap.

When I first arrived on the machine there was a lot of oil and actually I found a rag from previous technician.

Then I would check the main cylinder seals or the fitting at the bottom of the cylinder to ensure there isn't a leak there. I've seen multiple seals go bad on the lift cylinder due to overloading.

It's not the oil level. Oil level is actually around middle when platform completely lowered.

If the hydraulic reservoir is overfilled when lowering the lift, fluid will exit the relief holes on the hydraulics reservoir cap. It is actually a design to allow air to enter and leave the tank as the fluid level rises ans drops. My recommendation is to lift the platform fully and check the level, if it is still very high, drain some fluid. You will still want to leave atleast 5 to 10 cm of fluid at the bottom of the reservoir to ensure the pump won't run dry.