Replacing Moen 1248 Cartridge - retaining nut stuck

[saleler226]

Due to a faucet leak, I'm trying to replace a Moen 1248 cartridge. Moen sent the part and instructed on using the 14272 removal tool to remove the retainer nut before removing the cartridge.

However, the plastic retainer nut is extremely stuck. The 14272 tool was useless for this job. It just stripped the plastic. I've saw some advice to jam a chisel in there and twist. All that did was remove the inner layers of the retainer nut. The outer part of the retainer nut is still stuck on the valve and not moving.

How can I get the plastic nut to separate from the valve threads without damaging the valve? Appreciate any advice.

 

[salesy2k]

Did you ever figure it out, I'm in the same boat right now

 

[Sponsor]

 

[jccookii]

TLDR: Have replacement cartridge handy. Soak cartridge nut with vinegar, heat removal tool "teeth" with torch till near red hot and insert removal tool to melt in new openings for the tool teeth and remove.

So for those of you who, like me, found this and wanted to know what to do next...here is what I ended up doing.
I am not a plumber, so take this advice with a grain of salt...
I too had the plastic cartridge nut strip out when using the removal tool. I searched the web and found that most recommended breaking apart the cartridge nut with a soldering iron or chisel. I didn't have a chisel small enough or the needle end for a soldering iron to be able to do that, so I came up with this idea. I poured vinegar down into the valve body and let it sit for 30 minutes. I removed the majority of the vinegar with paper towels so the cartridge nut was showing. I modified the removal tool by drilling a hole through it so I could insert a screwdriver to use it for extra leverage. Next, while wearing a welding glove (or holding the tool with a pair of vice grips), I then took a propane torch and heated the metal teeth of the removal tool to near red hot and inserted it down the valve body. This melted in new tooth openings for the tool to be able to grab and unscrew the cartridge nut. I was able to remove it at this point, and though it was somewhat deformed, I was able to reuse it with a little trimming (waiting for my replacement cartridge nut to be delivered, and will replace it once it comes in).
Hope this helps you, and prevents you having to call a plumber to remove the plastic cartridge nut.