Hi Richard,
Thanks for the reply. We didn't renew the oil seals and I'm unable to answer on their condition (of the oil seals on the output flanges), or wear grooves on the seal paths, as we were working on replacing the transmission brake bands and a broken bus-bar spring. The breather holes on the top of the dip-stick were cleaned out by me, but I'll check again to make sure they're not fouled.
Our mechanic did mention that the next time we pull the unit we may have to replace the bearings, but in the meantime - which is the correct "snake-oil" to use as a short-term fix?
Cheers,
Chris