Loose tube sockets

I'm re-tubing my amp with new 6550C's. They are the same style tube I took out. But when I put the new ones in they fit very loose in the socket. The old tubes were nice and tight. I would think the new tube would be the same size and fit as tight.

What's going on?
Check the size of the pins on the tubes. They can vary. If you are running power tubes with pins smaller than the old ones be aware it could cause a run-a-way tube tooverheat/short out and damage your amp. If the pins are in fact the same size the metal clips in the sockets could have become expanded when you extracted the old tubes. You might try taking a tooth pick and inserting it on the outside of the clip and pushing it in. Be careful.

PS If you can't see a difference don't assume there is not one. The difference might only be detectible with a micrometer. And, FWIW since you don't give a brand name, JJ tubes have different size pins lately so if they are JJ's beware (actually I'm not even aware that JJ makes a 6550).

These are SED SV6550C's the same as the ones I took out.
I put the old tubes back in and they fit like they should, tight. The pins on the new tubes must be smaller. Re-tensioning the tube sockets maybe the thing to do.