If any one is interested we replaced the O-ring on the internal brake input plunger on my neighbors 1450 today. I had asked about it some time ago since I knew we had to replace it due to a leak. I had never replaced one before but once I see how easy it is I may replace some more on my Cubs when I do a hydro fluid change, just to be on the safe side..
Removing the bracket that pushes on the plunger was easy. Just remove the adjusting bolt completely and the shaft that holds the bracket will slide out, with a little persuasion. Remove the cotter key on the brake rod to the bracket and you can remove the entire bracket.
Once you remove the bracket there is a short small rod that pushes on a ball bearing, remove them and the O-ring assembly can be pulled out with a pair of needle nose pliers.
Now a smart man may have already drained the hydro fluid but if there are two of you one man can remove the O-ring assembly and another man can quickly place his hand with maybe some plastic over the opening and you wont lose much fluid.
The first man can remove the old O-ring from the assembly, clean it and put on a new O-ring. Then quickly replace the O-ring assembly in the rear end opening as soon as the second man removes his hand from the opening.
Then just re-assemble the bracket and make the brake adjustment per the manual, and top off the hydro fluid. I doubt we lost a 1/2 quart of hydro fluid.