Recently got a highly modified 8" f6 APM "Deluxe Achromat" OTA and I'm seeing Newton rings in the center of the elements, which to me mean they are touching. I'm thinking this is not a good thing.
I'm also seeing what looks to be two element spacers floating around between the elements, but also three where I'd expect them to be. I can see what looks to be the glue residue of the two floating spacers at the edges but they are in wierd places, one right next to one that is in the correct position and another all by itself. Makes me wonder what kind of aberrations APM was trying to address.