TMB 92 / Radian question

Using Radian eps (10,8, and 5mm) on my TMB 92 I notice an unusual abberation. Star images (especially in the 10 and 8mm)show a noticeable vertical elongation on inside focus during star testing. Outside focus does not really show a 90 degree rotation as in the classic astigmatic case. The 5mm shows just the opposite effect with the elongation occuring on outside focus. I'm really perplexed. Well corrected optics along with well corrected eps should not show oval (albeit slight)during star tests. Does anyone have any ideas???

Tim, I bought a new TMB 92 a while back (year ago) and it suffered from the baffling being askew. Light scatter was annoying on the planets similar to what you are describing. I sent it back and never reordered. Try some differrent eyepieces too before moving forward. Good luck! Paul