Congratulation!!
I have done many glow plugs on my old 606. The secret is lots of penetrating oil and having the engine completely hot and heat sunk.

I had some that squeaked and squealed all the way out. Real pucker factor.

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1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250