Henk,
That is a very wonky system done long ago by others and found wanting in reliability and consistency. But I offer you a much better solution here for the insult.
It looks like you have already drilled and tapped the worm cover to hold the worm bearing blocks in place, if this is true you will get better consistency by installing a in the outer bearing block using the well proven methods of either reducing the 4RZZ bearing's outer shell OD just enough to allow the bearing to float in the outer bearing block or by honing the outer bearing block enough to do the same thing, floating the bearings on a layer of fine lube, both work well. The Belleville spring disc is oriented with the large cone pressing on the worm bearing outer shell, you may need to put a shim under the small cone to get some preload depending on your particular outer bearing block cavity. Next you snug down the fasteners to tie the blocks firmly in the worm cover now acting as a bearing block carrier and at this point your worm should have zero endplay in the carrier and the entire assembly should behave as a solid single piece. You can stop here and you will have a massively improved worm carrier system and then just adjust the backlash on the mount after it has been chilled outside on a cold night in the usual way.??
But this next step should get you pretty close to where those with sprung gen II OPWs are. Your mount appears to have a drilled and tapped hole in the deck/base plate in line with the outer bearing block. If this hole has been drilled and tapped all the way through to the outer bearing block post you might find a to fit the tapped hole to make this setup behave as a spring loaded loaded worm system. The spring plunger if you find one small enough yet long enough would act on the outer bearing block post in the hole preloading the now mechanically bridged bearing blocks. You would need to use a fine grease under both blocks and under the bottom cap screws and set the cap screws the tiniest bit loose to allow the 0.001-0.002" movement needed to float the worm, it should not be loose but just able to move in and out. You will also want to use a mild thread adhesive on the retaining cap screws. If you cannot find a spring plunger small enough, I don't know the hole and thread size, you can in essence make your own by using a short piece of solid SS rod with an OD to closely fit the threaded hole and chased by a small block of rubber and caped with a long inside hex cap screw for an adjuster. Again you only need to allow 0.001"-0.002" of movement so this should be nearly as effective as the real spring OPWs.?
Cheers!
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Chip Louie Chief Daydreamer Imagination Hardware?
? ?Astropheric Weather Forecast - South Pasadena, CA?
Chip Louie