Oof!!!

The first thing is that I don't think you want heavy grease in the pawls. Perhaps some very light oil/lube.

I tend to like Lucas ATF transmission leakstop oil for that kind of application, but try some moderately high viscosity oil instead of grease, and see how it works. Or, even a low viscosity oil, or even dry.

As far as finding replacement freehubs, I've found in the past that there was a large amount of similarity between different manufactures of external pawl sealed bearing freehubs. Obviously bearing size, and a few other details are important.

When I type in "novatec xd freehub" into an E-Bay search, it comes up with several options.

This page lists their type "B" freehubs as being compatible with the Novatec D772 SB hubs (either 11 speed or 12 speed available). Freehubs appear to have 4 pawls.

https://www.ebay.com/itm/162587936085

This one appears to have 6 pawl freehubs.
https://www.ebay.com/itm/302364181571

If you wish to try a 6 pawl freehub, then count the number of teeth on the ratchet. If it is divisible by 6 (and probably 12), then it likely would work with a 6 pawl freehub. If ratchet isn't divisible by 6, then stick with the 4 pawl freehub (teeth divisible by 4).

Some of these are coming from China, which is usually fine, but can incur a shipping delay. I think this is the middle of the Chinese New Year which usually adds an additional delay.