SC2 arcade stick maintenance question

I have a question for someone who knows about modding/repairing arcade sticks.

Basically, I bought a 2nd SC2 Hori stick for the PS2. It seems to be in a different batch to my first (which is lovely btw) as the artwork on the plexiglass is lighter than my other one. Anyway, the stick was a bit stiff, so I tried loosening it up a bit (loads of 360s etc). It got looser but started squeaking. So last night I took the thing apart…

I think the problem is that the ball and socket arrangement (just above the spring) does not move smoothly, but rubs when you move the stick. The spring tension is fine now, and the stick is ok to use when playing normally. The only problem is that when you move the stick slowly (past when the switches have been depressed) it 'sticks' and does not move smoothly to its extreme. It also makes a squeaking sound, which says to me that something is rubbing when it shouldn't. As I said, when playing VF4e it doesn't matter as you tend to make quick movements (preferably not using the whole stick range). But, I want my new stick to be sorted out.

What do I need to do? Remove the stick and spring assembly again and liberally apply WD40 (a popular lubricant that comes in a can - in case it is not sold in the US)? Any other suggestions as to why the stick might not be smooth? Could it be to do with the spring?

Any suggestions would be gratefully recieved.

Thanks