How do I remove the spacer of my MP40?

[rnd4]

Breaking down a long-neglected tank that ran an MP40. I’ve removed the wet side, and the motor part of the dry side came off easily, as expected. 
 

But the spacer is stuck tight. How does one remove it from the glass? 

[seabass]

Can you twist it off?  I might try spaying a bit of vinegar around it, to maybe help dissolve any mineral deposits which might be holding it on.

 

Or maybe take a 1x2 (or other small piece of wood) placed against the spacer, then gently tap the wood with a hammer.  Lastly, maybe you could try to gently get a razor blade between the spacer and the glass.

[Tired]

If that doesn't work, I wonder if some version of the trick where you warm up the jar lid might work. The thing where you run the lid of a stuck jar under warm water to make it expand. Maybe putting either fairly warm water, or outright ice, on the plastic would help? Getting it to change sizes could help loosen it. 

[seabass]

Following Tired's thought, a hair dryer could heat it up.