Here's what worked for me in terms of suspension service. Fidled around with the springs and finally came to the consclusion that something was wrong and it was going to take more than a "tweak" to set it right. Dealer buddy gave me some black Linn springs and rubber grommets . Removed arm and both platters , stoppered bearing with rubber cork , flipped it upside down. Can't emphasize this enough - once upside down the suspension is pretty darn easy to deal with - try to fight ol ma gravity with it bottom down and it's just frustrating.Removed old spring assemblies , salvaged foam plugs from inside springs , these are glued in at the top and bottom - so you'll have to pull them out. Used IPA to clean old glue patches on chassis - wasn't trying for surgically clean - just clean enough to be confident the new glue will stick. Used GE RTV silicone sealant to glue spring to new rubber bushing and then used sealant to glue that to the chassis. Lightly glued smaller rubber gromet to spring where it gets the nylon cup's post inserted.Left for 24 hours (SWMBO was not amused - her dining room table). From there - lightly lubbed the threads for the nylon cups - threaded them in a equal amount. Turned table rightside up ,set on LP-12 service frame , installed arm , adjusted suspension to balance it even. Other than dealing with the impressively stupid base connector on the SME series 2 improved ( ended up sticking a wire tie block to the bottom of the chassis and wiretieng (tie wrapping) the arm's cable to that - with a bit of slack between tie wrap and arm so that it could still move freely.Re-installed masonite bottom plate. Installed DL-110 Denon - it works nicely. I can bounce pretty vigorously on both heels in front of my equipment cabinet - while playing the table will move up and down by a good 1/4" (6mm.) or so -not a trace of a skip or burp from it. Suspension appears to be moving entirely vertically.
Nice result. As a long time (decades) LP-12 user - the bass on the Thorens 125 just beats the ol Linn hollow -seems to go deeper and with much better impact and authority. So - I guess it's time to go to work on the LP-12 now!