Loose Briggs exhaust valve seat--option?

The AC riding mower at a Habitat for Humanity site had zero compression. Removed the head of the B&S 191707 engine and discovered that the valve seat was rattling around on the exhaust valve. The seat feels loose in the block when it is in the correct place. I assume that the seats are pressed in. Any suggestions on a fix? Would JB Weld handle the temperature?
Would appreciate any suggestions. Thanks.
JOP

 

I think that JB-weld would handle the heat...BUT less its a very thin lear it would interfear with the valve clearance too much.I'm not sure about this way anyway.the way I alway repair such... is to clean the seat & the hloe where it goes real good,then mash it into place and then just thke a pin-punch and hammer, go around the seat pinging a dimple at every hour (as a face of a clock).This will tighted the seat,I've never had any to come back out done this way.

 

You can mix some JB weld (regular, not the JB quick) and put the seat in place with it...sparingly. Let the valve spring pull the valve down tight on the seat to hold it in place and tap the valve face a little to align the seat with the valve face and squeeze out the excess JB weld and wipe it off, then use a center punch around the edge of the seat in the aluminum block to make dimples around the seat (swelling the aluminum enough to hold the seat in tight). You shouldn't have any problem after this repair except the small possibility of having to lap the valve surface.