Long post covering the background, answer at the bottom of the post. FYI.
Been shooting this rifle for a couple of years. Not a lot, but never had an issue until a couple of weeks ago. Have been shooting Greek surplus bought in the clips, until a couple of weeks ago when I finally got around to shooting it with some reloads in the reused Greek surplus clips.
Just for background the reloads were civilian R-P cases, CCI 34 primers, IMR 4895 and 147 grn. FMJBT bullets. Yeah, I know, why mention the reloads. The only reason I did was I've read the Greek surplus clips won't work with anything but Greek surplus brass but they seem to work fine with R-P brass.
Back to the clip ejection issue. I'd fired 3 or 4 clips when one didn't eject. I couldn't pull it out either and had to drop the trigger assembly out the bottom of the stock to get the clip out. I put the trigger assembly back in and went on shooting with no more issues. Things got busy and I grabbed some loose reloads and filled the clips back up. A little bit later I had the same problem and used the same "fix" to remove the clip. I couldn't see (without my glasses) why the clip wouldn't come out. Again, I got busy and refilled the clips without identifying what I though was THE problem clip.
This weekend I pulled the bandoleers out and started going through them (darn near got a blister on my right index finger from working the rounds through the rifle one round at a time. Got through two bandoleers with no issue. Into the third bandoleer I thought I found THE problem clip. I couldn't see any difference between it and the others so I continued working through the remaining clips in that bandoleer and ran across a second one a couple clips later. At that point (since I had put my glasses on trying to see what was wrong with the first "bad" clip I could see the clip ejection spring had popped up and inside the clip and that was what was keeping me from pulling the clips out when they didn't eject properly.
Absolutely no visible (to me) difference in the clips.
I got my spare trigger assembly (might as well carry some spare parts around in that big old hard case) out and held them up side by side and the problem was immediately obvious. The problem trigger assembly clip ejection spring is not as long as the spare after the 90 degree left bend that fits under the clip and pushes it up.
The problem spring worked for a couple years with no issue and worked with most clips after the problem started. The length difference is quite obvious when compared to a "good" spring. Now to dig a spare clip ejection spring out of the parts box and tear that trigger assembly down. Oh, all the springs in that trigger assembly are "new" as of a couple of years ago when I started shooting this rifle.