Have a leak where the shaft comes through the firewall and want to drain the fluid and refill with Lucas power steering leak stuff, so how do I drain the whole system?
1995 TS, 4 cyl.
The leak isn't really very bad but messes the concrete driveway

Not sure if the TR/TS racks are the same as TP series but i removed mine a few months back from the TP and removed that top seal and got a replacement at my local bearing/seal company.They just measured it up and found a replacement. A full seal kit is around $120 to do the full rack etc but if the rack itself is good no need to do the lot.
That seal stop leak stuff alot of the time does not do much.
If your handy with spanners the seal is about the same price as the stop leak can.
Hard to drain the system completely as it stays inside the rack. I have only ever flushed thru to put new fluid in.
Usually remove the return hose to the tank and stick it in a container and start the motor and keep topping up the tank as it flushes thru until i get new fluid exiting the return hose. Reconnect hose and top to required level. Vee

TSs leak there, end of story.
Shaft wears, seal leaks. Stop leak won't fix it, it just swells seals a bit, by the time it leaks it's too far gone. If it is really bad shop around for a reconditioned rack.