I purchased a 760 Logix Electronic 255 Metered Softener Control, and attempted to install it this weekend, (I replaced an old 155 valve). I left the bypass valve attached to the plumbing so I could leave the water in use in my home, and mated the metered valve to the bypass valve with silicone lubricated O rings that were supplied, it leaked. I repeated this operation 3 times and was able to slow the leak but not stop it. I need a new set of O Rings (even though the supplied ones appear fine). Also with all the assembly /disassembly the 4 bolts and nuts are pretty much shot and I would like replacements for them as well.

Do you have advice to offer? Should I turn off the house service and disconnect the bypass valve? If so I will need new gaskets or O Rings for that as well.

MATING new parts to older parts can be a challenge with Autotrol valves.

The only advice is that the o-ring must be placed on the "male" portion ( in your case the rear of the Turbine Meter Assembly ) and the By Pass carefully "PRESSED" onto the o-rings.

And the bolting needs to be first "snug" by hand, and then ALTERNATE tightening of the 4 bolts / nuts.

Work around the 4 points about 3 times, and they must be as tight as you can get them.

And even then, I've had similar slow leak issues when attempting to mate the old parts to the new parts.

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Be sure you do not "nick" or damage the 3 o-rings in any way.

And if problem continues, then my only suggestion would be to replace the By Pass also. And the new By Pass would include new o-rings, and new nut / bolts.

see:

By_Pass_256_New_Style_For_Autotrol_155_And_255_ap1040769

and yes, ( 2 ) 54F gaskets would be recommended at the same time,

Sold separately are the Adapters ( 54F,55F,56F ) are still available and are sold in KITS ( pair of each of the 3 items )

The replacement By Pass is called the 256 and will fit both 155 and 255 valve bodies, but not 163, or 168.