Dumb Question - 250 Watt MH - Replacing the bulb

[phar]

So a friend of mine gave me a Aquamedic 250 Watt MH fixture. I thought I'd upgrade from my 150 Watt. I bought some new bulbs for it but they don't seem to snap in. They push down into place but kind of rest there. I know as soon as a I flip the fixture they are going to fall out. They almost feel like they are hitting something in the plug.
I've pushed down with moderate pressure but nothing seems to snap into place. I've pushed down as hard as I dare without breaking them.
What am I missing here?

[cuz]

can you loosen the screws on one end of the "sockets"??
this usually helps, then just tighten them back up once the bulb is in proper.

[phar]

I've tried that. I've actually completely unscrewed the sockets / seats from the fixture to make things easier but it didn't seem to help.

[cuz]

the old bulb didn't break off a small piece and leave it behind either?

[Skimmerking]

that is why that I hate the DE 250's if the 250's were like the 150's i would go back to them.

[Coleus]

well I can't remmber if the 250W will snap, try to turn upside down and see if it fall out (but a pillow or something soft under so you don't break the bulb if all out) :-)

I think i experienced the same with my maristar fixture. the metal plate just hold on to the bulbs