Resolved SC-3 Starchaser - first-light issue

My initial efforts to get a candidate star onto the sensor of my new SC-3 StarChaser for purposes of setting focus haven't been successful. Nothing resembling a possible star, including blobs of any size or shape, shows up in any of my exposures. I've tried subs of up to 5-seconds with no stars. As for the starfield, I've tried Brocchi's Cluster, which fills the field with stars on my main camera, Jupiter - which should at least show some stray light even if it's only close-by, and finally, the Moon. The Moon gave me a small crescent of light at the bottom of the image, but when I repositioned the scope by about 20-arc-minutes the image didn't shift at all, so I can't interpret the results of that experiment.

Which makes me wonder if my secondary mirror is putting the pick-off mirror under a shadow. My main imaging scope is a Takahashi CCA250 (corrected Cassegrain) at 1250mm focal length, f/5. The central obstruction is .58 relative to diameter of the primary. Checking with Darren at Takahashi, the image circle at the focal plane is 88mm, which is larger than the 3-inch aperture of my STXL-16200. I'm posting a snapshot taken down the front of the optical tube which shows (I think) the placement of the pickoff mirror in the light path. In the photo, as well as in all my trials, the pickoff mirror is at full extension.

Can you please offer some advice? Thank you!

 

Hi Doug,
Yes, I read the 9/25 post from Russ Croman and checked the pick-off mirror. There is no protective film on it. Also, I did point the scope at the Moon and got a small crescent of light at the bottom edge of the image. Thinking it was the unfocused Moon, I moved the scope in all four directions by about 10 arc-minutes to see if I could center it. No luck - the identical crescent-shaped light pattern didn’t move. Don’t know what to make of that.
Jerry

 

Attached...

 

Sorry Doug, I thought I attached this to my previous! Here's the side view...

 

Thank you, Doug. Clouds have just rolled in today, and they may take a few days to clear out. I’ll report back!

 

Clouds cleared out after midnight, so I was able to test your suggestion to change the mirror position. Got stars! Pick-off mirror fully retracted. M45 was a big help...

Thank you for walking me through this, Doug - it looks like this one is resolved!