Hi Ian,
If you are worried that the fork will jamb when the slider is pushed up the sanction, it seems of very little value to attempt to set the fork alignment up while the slider is forced to the tip of the stanchion by the spring. It is much better to lock everything into position while the slider is pushed all of the way up the stanchion, however this is almost impossible to do with the forks fully assembled as trying to overcome the spring pressure is difficult.
I have had good success with this method.
Slacken all clamps and nuts so they are just in contact, except the top clamps.
Place a jack under the front of the engine and support the bike.
Remove the top nuts and springs, and fork oil if you are changing it.
Lower the bike gently with the jack so that the sliders are fully pushed up the stanchions.
Check the yokes (triple trees) are in line, and then tighten the bolts and clamps, starting at the wheel spindle and working upwards.
Raise the bike up with the jack, so the forks are fully extended.
Lift the wheel/fork assembly, and drop it down several times, any tightness or binding can easily be felt as you have no spring pressure to overcome.
If you are happy replace the springs, fork oil and top nuts.
If you had been suffering from a harsh fork, the best thing to do is match the spring rate to the weight on the front wheel when you are riding, this is the fundamental base line of Suspension tuning. The problem we have with our old Meriden Triumphs is you cannot get a spring that is not the standard rate anywhere, therefore when tuning the suspension you are handicapped from the start.
There are a couple of things you can do, oil viscosity, time after time in different threads forum members keep telling us that they have the best results with sae 7.5 oil and Bell Ray is the most popular brand. I would not dismiss this information, it comes from too many respected sources.
Differences in Oil level can have a surprising effect on fork action as it changes the amount of air above the oil that acts like a second progressive spring when the forks are compressed. For a softer fork less oil, for a harder fork more oil, small changes make quite a difference.
Overfilling first and then removing the oil in 10ml steps through the drains is easier than underfilling and trying to top up.
Start at about 230ml (hard ride) then ride, remove 10ml, ride-keep repeating this until you are happy (happier)with your fork action.
If you cannot find a setting you are content with, change the oil for one with a different viscosity and start the process again.
It is better to use the same stretch of road for comparison every time.
Regards
Peg.