728-VT Nut for tramming head

[COMachinist]

Try CRC knocker lose spray to help get it free. It only takes about 2 or 3 drops on most jobs. When that don’t work, I heat the bolt or nut to about180* then put a few drops on it let sit 5/10 min and then it will come out, never had it fail yet.
CH

 

[6061T6]

Okay, I ordered the B'laster PB penetrating oil, which will be here Thursday. I also ordered an extra-long ratcheting wrench with 17mm and 19mm ends (the nut in question is 19mm). https://www.amazon.com/TEKTON-WRN77113-Flex-Head-Ratcheting-Wrench/dp/B01F512HQS

The wrench gets here tomorrow, maybe the extra leverage will make a difference. I'll update my post as I try things.

Thanks for this awesome suggestion!
I bought the exact same wrench. The nut assembly was already marinating in PB blaster for a couple of days.
The wrench made short work of it.