The later 12s have a brake band and drum on the shaft from the control box. BUT the older 12s dont. If blade is dropping when the arms are horizontal what do you do on an early 8t. Worm gear and bull gear are in  good shape. You can lift the front end without kicking.

Hi, oldbeek.
I would suggest that first place to look would be the bearing adjustment for the worm gear that drives the bull gear on the back end of the horizontal blade lift shaft. I can't remember what adjustment the 8Ts had, whether screw and lock nut or the earlier cap and shims arrangement. Either way, you need to have a little weight on the lift arm to be able set the bearing clearance 'coz that pulls the worm inboard into the inner bearing leaving all the clearance at the outer bearing.

DO NOT over-tighten this bearing or the control lever will boot you through the back of the cab or throw you through the windshield.

Another thing that can cause the dropping is severely worn teeth on the blade lift bull gear which is the big one on the front of the cab,

That said, pretty much all of this stuff is in this post:

www.acmoc.org/bb/discussion-d72/11465-home-at-last#91423

Hope this helps.

Just my 0.02.

Hi, oldbeek.
If the above doesn't work, the next thing I'd be looking at would the amount of wear on the blade lift bull gear in the area where the worm drive engages it when the arm is horizontal. This would involve marking the lift shaft so that you know when you have that section up to the inspection plug opening at the top, loosening the lift arm clamps, removing the key and rotating the bull gear and shaft until those teeth come to the top where you can inspect them.

(You might need to remove the inspection opening plug in the top of the housing to be able to see the bull gear teeth. LOL.)

Just my 0.02.