I had to clean one of these for JCB. I thought they had a tank to clean that I would be able to drive the van into and stand up in!!!!!!
They were exporting a whacker plate that had been rejected by customs and they would not allow it to fly because it smelled of diesel.
I took it to my unit, put a detergent in it, rinsed, put washing up liquid in it, for a fragrance and then rinsed and steam cleaned.
Don't be afraid to use a detergent, just rinse well and allow to dry before refitting.
Rob