It's not particularly difficult to remove the steering box. Firstly you'll need to remove the trafficator assembly complete with wiring, so that you can remove the steering wheel retaining cir-clip and wheel.
Removing the steering drag link ball joint and three mounting bolts is easier if you remove the inner aluminium wheel box first. It's also easier to slide the steering box and column downwards once the left front shock absorber has been removed.
As for replacing the seal there is a good guide here.
http://www.macysgarage.com/myweb6/steering_box.htmhttp:// This guide is for a TR3 box but they are identical to an Ace unit.
While you have the box out it's a very good idea to strip and inspect the whole unit as usually there will be some wear in the bronze bushing for the rocker shaft and on the faces of the tapered peg. I've also found broken up cages on the upper and lower inner column thrust bearings before.
As you suggest a good project to tackle over the Winter.
Regards,
Luke.
