I've done the same with one of mine, spring wise, and replaced the Oring with one of the manufactured hard teflon ones from the guy that sells them on ED/DCS forums. The Hall sensors have their own different sorts of issues from POTS, they aren't invulnerable to failure by any means, just search online for Warthog issues in that regard and you'll get the phone book. It's just less frequent than POTS, however I will say the post CH sell off manufactured CH products last a LONG time, I have a Fighterstick that is over 10 years old and used every day and is still working like new. I have had several Warthogs, 1 is new, and the other 2 have had major sticktion issues. One I've done the spring removal, re grease with a grease NOT recommended by TM, as that sucks, and replaced the oring. It works alright now, but nothing like a new one does/did/. Their workmanship on the internals is terrible, and again, the gimbal is garbage IMO.
Did you mess with anything other than the springs with your stick? If not, you will, eventually. It just takes time, it's random and unpredictable, I had one that after maybe 200 hours of use needed a complete overhaul, the other was my first, and lasted 5 years before getting sticktion badly. No issues with the sensors on any of the 3 sticks I have, and 2 throttles.
VKB has impressed me, look at Blade's post here comparing his various sticks from VKB (jealous) to his Warthog/etc. I think a Warthog stick, with that new Gunfighter base/gimbal = best of both worlds, and what I'll be after when my "good" Warthog goes down. The VKB pedals I have are getting stomped on every day, and so far so good - not as pretty as the Slaw or MFGs, but work as well and are simpler and more fine motorskill dependent movement wise. We'll see I guess how the Gunfighter turns out, but I do wish TM would get off their butts and make an advanced/better WH system. CH too, if they made a Hall sensor CH hotas system...I'd buy it, for certain.