Steering play/ 4 bolt PAS

Hi all, after being inspired by all the great pics from last weekends trip to Wales! I'm sorting my 90 out.
I've done the brakes and wheel bearings right round- thanks to busters how to threads.
So now I'm onto my suspension and steering- which is the reason for thread.
I have some excessive play in steering wheel and after a lot of searching on here and google I've come to the conclusion my lower steering uj is shot- I'm picking one up in morning along with TRE's and a new terra firma RTC steering damper.
But I also noticed my drop arm has about 5-10 mm of movement (up&down) where it meets the shaft from PAS box (4bolt)- is this right or should it be tight ( no movement)? There is a locking washer on the nut.- can I just tighten this nut right up?
The drop arm ball joint gaiter is loose ( elastic bands have come loose) so I've ordered one of these aswell.- not looking forward to getting this off haha.
After doing the above if there is still excessive play then I think it's the PAS box- as it has a leak. I've found some seal kits for the PAS box- is this worth doing or is it false economy and I should just bite the bullet and buy a box- there a bit pricey!!
Sorry for long post but any input from you knowledgable peeps will be gratefully appreciated.
Thanks
Chris

There should be no movement like that at the drop arm/steering box shaft. Bend the washer away from the nut and tighten. Don't forget to bend the washer back to the nut when tightened otherwise it WILL loosen again. Best to get someone in the cab to move the steering very slightly from side to side whilst your underneath just to see exactily where the play is. I wouldn't bother with a seal repair kit for the steering box as it will be no time until it leaks again - get a new or recon unit, there are a few places which will do an exchange for your old unit like MM4X4.

seal replacement is perfectly viable and can be done on the vehicle as long as drop arm can be removed (this is usually the most difficult bit )and shaft isnt pitted and corroded were seal runs on shaft,its only the poor surface of shaft sometimes makes the job short term ,seal can be replaced by removing dirt seal ,circlip ,running engine and turning steering wheel in lock, oil will blow seal out (obviously with container underneathto catch oil),new seal can then be carefully fitted in the steel washer then circlip

As jamesmartin says but the seal usually goes because the shaft is pitted and corroded !!

Cheers guys. Undid nut yesterday and the drop arm just fell off- thank god. The splines on shaft and drop arm are ok, so I just put back on with a new tab washer- it tightened right up! I changed lower steering uj aswell and now It feels like a different 90- only about 5-10 mm play in steering wheel. I'm made up!
Do I have to take the PAS box apart to find out if shaft is pitted or corroded?

Sorry forgot to add- the PAS box leaks from bottom and also at the top!
So I think i would have to do a full seal kit!