collimation again?????????

Once again LOL. OK I replace the colimation screws on my LX200 with knobs "months" ago. I had some problems that I worked out with the help of the fine people here. the main problem I had was pinched optics and that has been resolved.
Went out last night and it was the clearest night I seen in the south US in months. so I set up and tweaked the collimation after about 2 hours of cool down. I must say I got it very close IMO. So now I pop in the diagonal and try different EP's and the collimation is out. its out enough that anyone would have seen it.
The problem is that before I replaced the screws I did not have this problem with the diagonal.??????????????
Anyone one have any ideas?
Should I just collimate it with the diagonal in it seeing that I don't have any astrophotography equipment yet?
are there any collimation pro's living in the South Carolina area that can help me in person??

Had the same problem with my old 2120 LX5. Sorry to say, the best choice for me was to collimate without the diagonal, which was later found to be defective. Ended up using a visual back and refractor diagonal. Watch out for gross mirror flop and sloppy focuser, as collimated in one position may not be in another. Too much play on the baffle tube can wreak havoc!

Collimate without the diagonal. The main purpose of collimation is to align the optical elements of the scope. This is critical because this is what gives you the image and if it's off then the image suffers. Now if you have your scope collimated and you stick in your diagonal and it looks off then the diagonal is messed up, if you try compensating by mis-aligning the scopes optics then the image will suffer because you just un-did your collimation.

The reason it would look out of collimation in your diagonal could be because the mirror or prism is out of whack and is not giving you the full light cone to the eyepiece not because the scope is all of sudden out of collimation again.

I hope this makes sense,
Robert W.

Thanks for the replies. I guess I will have to keep working on it. I guess I should have said what acc's I am using with the scope. I have the big 2" visual back from AP and I'm using an Antares diagonal. I use a 2" EP to collimate so I don't have any play in it from a 1 1/4 adapter. I guess my main question would be, why is this happening now when it didn't happen before??????????