So, a client has purchased a house. There are about 10 6" recessed lights installed. They went in about 20 years ago, would be my guess. (There was some newspaper stuffed in a wall to allow plaster to be applied, that and the look of the lights and the NM gets me pretty confident on this.)

I don't know if they are really insulation contact rated. They have thermostats in them, and they certainly are buried in insulation with a 65watt bulb in them, without any tendency to blink. And it is hot here just now.

What they certainly ARE NOT is air tight. The cans are just punched through with holes and slots.

They are new work, not retrofit, so I'm reluctant to just tear them out.

The client wants to retrofit with LED trims.

I'm wondering: of the 6 that we intend to keep (we don't like the placement of the others) can I just remove the three screws that hold them to their frames and drop them into the room (mechanically, yes, I can) and use aluminum duct tape to close up the various slots, then shove them back up into the attic?

I'm just looking to save the client a few bucks and me some time. He wants another 18 cans installed, got plenty of work to do.