I had a peek through the eyepiece, it was suffering internal reflection, i.e. diamond-shaped glares on the image when in focus.
As such, I left it alone at the time to contemplate what I want to do with it. I have the option to flex the primary mirror with a screw or push forward the main mirror and do away with the Barlow.
Fast forward to last week, I removed the doublet Barlow lens, darken the lens edge and test the scope again, the internal reflection glares have disappeared, but the outer 40% field of view was fuzzy. I swapped the doublet Barlow lens with either a glass or plastic singlet Barlows, the view improved to around the outer 25% field of view being fuzzy. I then decided to remove the focuser tube and the Barlow, and dipped the eyepiece into the drawtube bracket to achieve focus, and could see sharpness almost to the edge of the field.
Eureka! The decision is simple, the primary is not bad for a spherical mirror, I am going to move the primary mirror forward closer to the secondary mirror to achieve focus. Yes, the central obstruction will increase, but doing away with the Barlow will remove chromatic and its induced spherical aberration and I will have a short-tube rich field telescope equivalent to a 3-inch frac, which I think I will enjoy.
To push the mirror forward I added the spiral paper tube of a masking tape of around 9cm. Cut and glue two circles of hard transparent plastic to the spiral and cover it on both ends, and then glued one end of the paper tube to the mirror and the other end to the black plastic backplate. I put black tape around the primary mirror edge. After testing the now Barlow-less scope with 6mm, 10mm, 20mm, 25mm, and 30mm eyepieces during the day, I am very happy with its performance. Sharpness to the edge for the lower power eyepieces. Slight blurriness around the edge for the 6mm but insignificant for me. I am looking forward to testing my rich field spherical reflector at night.
As such, these 114mm short-tube scope are not a lost cause if you pick up or end up with one.
Clear skies! @@
Bill