I bought my Venco No.5 wheel new in 1999 from Pottery Supplies and have never had any issues with it. But, as it hasn't been used for so long, I phoned and asked them if there was anything I needed to be aware of before I started it up. They suggested that perished grommets would be one thing to look out for. So, I checked the grommets on my wheel, and they did look a bit shrunken, but I decided to take my chances. I ran the wheel for a few minutes while I polished the wheel head with silicone carbide paper, and upon finishing, found most of my grommets on the floor in small black piles beneath the pedal and wheel body.
So, I ordered 4 small grommets, 4 large grommets, 2 o-rings, and 2 fibre washers.
I'm awaiting their delivery as I type.