Powder coated top plate and transformer bell - grounding?

[Ty53650]

I had top plate (both sides) and entire transformer bell/cap (both sides) powder coated, and now I'm unsure of what to scrape down to bare metal for grounding purposes?  Perhaps I should've looked into this before having them coated, doh!  Is the transformer bell ok being coated or does the underside need scraping to bare metal?

Where on top plate do I need to scrape to bare metal?

Thanks!

Ty

[Doc B.]

The bell should have continuity with the lam stack, and the also with the lock washer and screw, so that it is all grounded to the chassis safety ground. Scraping the powder coat off the underside around the hole where that grounded screw goes through and under the screw head on top of the bell would be best. Depending upon the thickness of the powdercoat you might get away with a toothed lock washer on top and bottom of that hole, if you make sure the screw is tightened enough to make the washers bite through and contact the metal of the bell. You can check that with a continuity tester (aka an ohmmeter).

[Ty53650]

Thanks Doc,

So there's only one area on the underside of the top plate that needs scrapping to bare metal? 

And to confirm, the bell should be scrapped bare underneath the 4 screws holding it to the transformer body?