25.4mm doesn’t really work. I would say it doesn’t work but, 1 or 2 people have made it work somehow. I’m not sure how It should really throw off the center assembly. You might want to check your extruder steps. Look up the 100mm filament test. Sounds like you might be over extruding.
Try looking for things other than conduit, like closet rods or shower rods. Try ebay. 25mm stainless is out there.