[R-390] R390A Cosmos disassembly question and a second question too!

[wa3frp at aol.com]

I've decided to keep going in my efforts to restore my R390A.  So far I've been able to get the front panel off and that was a lot less complicated than I thought that it would be.  I've also removed the RF deck, cleaned and checked the position of the RF bandswitch and the crystal oscillator bandswitch. So far so good.

Now, I'm working to open my Cosmos PTO as I am going to have to remove a turn, maybe two, from the endpoint adjustment coil so I can correctly set the endpoint.  In doing so, I've found a lot of documentation on how to adjust the endpoint but not a lot of documentation on how to get into the inner sanctum.  I've gotten as far as unsoldering the two heater wires and the heater system is free BUT now I can't figure out of the final metal chamber is just stuck or is a tight fit or is possibly a screw on.  I'm not about to use maximum force as I don't have a good backup plan if thing go badly.  So, is there a trick?  Any advice is appreciated.

Also, I was surprised to find that my Cosmos was assembled and then pressurized with 15 pounds of dry nitrogen. (This was on the warning label).  The nitrogen has long since dissipated but I'd like to know if others have repressurized after assembly or not. Interesting to note that I haven't seen this mentioned in any document I've read so far. 

Thanks and 73
Russ WA3FRP