My early 80s greymarket Yanmar 2420D with OEM Toyoda power assisted recirculating ball steering gear box is leaking hydraulic fluid under presure out the steering shaft seal. The actual assist mechanism looks very similar to the one on my Porsche rack and pinion so it must be a conventional design. There are two white plastic square cut seals arround the unit between the exterior housing and the assist assembly. These seal look a lot like the ones you see on an automatic transmission servo assembly. The seal on the top that the hydraulic oil is coming out of is a conventional oil seal. I replaced that seal and cleaned up the pitted shaft but it made no difference. Looking at the design I am assuming that the hydraulic pressure is to be maintained between the square cut plastic rings and not allowed to get to the conventional oil seal, right? I can't imagine that a standard oil seal would be designed to hold back hydraulic pressure. My real problem is that power steering is a rare option and I can't find a grey market dealer with any reference for the power steering box or parts listings. Hoping someone is familar with this style of Toyoda brand power steering gear and will know where I can go for help. Thanks