Hi javalinadave, I feel your pain! I also am looking for Mec-Gar mags and they seem to be as rare as red frogs hairs!
But, as for proper function on your original mag, it can be revised and should work as designed? If you are set on a replacement that has the best chance of working correctly, the two best choices are original "fxo" & "code 122" mags, or, the last factory produced mag. for the 06/29 Swiss luger. I personally think they are the best of all the original Luger mags. But, a new Mec-Gar is better than both! Good luck, best to you, til....lat'r.....GT