I've decided to electrify it with another Tongsheng and will be sharing the battery with the Drypod2. To that end I've bought a second base. This will need bracing round both sides with one side being quickly removeable to get the battery in and out.
It's very noticeable how much smoother and lighter the steering is after sorting that front mechanism.
My mum is elderly and frail and is taking a large portion of my time these days. The Polish seat never arrived, I suspect due to poor customs paperwork from the maker so I'll resort to a mesh seat I made previously.