Pinched Optics? Celestron 102 HD

Hope somebody can help out. When I use 30 and 35mm Ultimas in my 102HD, I get ellipses when out of focus on all stars. On the other hand, when I go to higher power eyepieces, out of focus stars are quite round with many rings. However, I can't quite get pinpoint focus on any stars with any eyepieces. Wonder if this is pinched optics or typical chromatic aberation with the scope. Using a Sirius MV-1 filter in the diagonal. Removing it doesn't seem to change anything.

Help would be appreciated.

Thanks

Howard