Help for vintage Omega 166.070

Good morning everyone and I thank in advance who can help me. I bought a vintage omega 166.070, but I noticed that the movement together with the dial move slightly inside the case. I took it to the watchmaker who, after taking it apart, told me that it does not have the original glass and there is no tension ring which, in his opinion, should avoid that small movement inside of the case. is this correct in your experience?
in the photo you can see that there is some "air" between the case and the dial.

Use the reference number and caliber number to order a proper crystal

Also check movement clamps to make sure they're tight

DON

I bought the generic glass but it shows the right omega reference. the question I ask the more experienced is: can the glass with the right tension ring really correct the problem of the small movement inside the case? The watchmaker took it apart in front of my eyes and told me that according to him this is the problem. what do you think? thank you

Yes, he did

Ring should just be touching the dial and should add the extra bit of force to hold in place

DON

the clamps could be lose; I think this red needs a crystal with a recess otherwis the dial will be wobbling;
it's one of these models with a dial smaller than the case opening even if it's 0,3mm difference. the dial is applied on th crystla ring;