Good luck, Eric. I find collimating my Schmidt Newtonian to be a right royal pain. I keep reading how easy it is - and then there's the reality.
I can't say for sure if you've got collimation problems. The example images you posted look like what I see through the MPCC when my scope needs collimation. When I'm collimated the wierd shape of the stars disappears and I get round stars right across the field of view.
BTW I can now get good, repeatable, and easy collimation of the primary mirror by using a device called a Barlowed laser. Sounds complex but it's just an ordinary barlow with a paper disc stuck to the end. A hole is made in the centre so laser light can come through. If you have a centre-spot on your primary mirror this barlowed laser creates a shadow of the centre-spot on the paper disc. This shadow is unaffected by focuser slop or the laser being incorrectly seated in the focuser. The efect is to give a more accurate collimation of the primary.
The LXD-75's secondary, for me is a nightmare at the moment. When I touch the secondary screws the whole secondary mirror will spin !
It's very difficult to precisely collimate a secondary that's doing that!