Barry,
I had my main mast pad changed in January this year in Martinique. I watched and here is what they did.

The jack system they had was specially made for the job. It was a single hand pump for the hydraulic, it was connected to two cylinders, one for each side of the mast. They placed large hard wood blocks on deck to distribute the load, on each side of the mast. The jack cylinders went on top of these blocks, and there was a custom made wood block that fit under the main winch on each side of the mast. When they pumped the jack, each side lifted exactly the same. They lifted it only about 35 or 40 cm, cleaned out the old pad and slid in the new one.

You might not want to be putting 5200 under the mast because it will be difficult to clean out with that limited space to work under the foot. On the outside of the mast might be OK.

My original pad was completely dissolved from age. I think the mast settled down that amount, and caused the rig to be loose. After installing the new pad, they tuned the rig using a tension gauge. I think they did a very good, professional job.

Bob Hodgins
Amel 54 #31
Currently in Raiatea, French Polynesia