He has the R2 retainer. Earlier tractor have R1 retainers and they are the ones that have the problem with loose seal fitment , hence the rework. I rebuilt by 52 long before this Forum and the seal "just" fit in like the rings in one of those carnival games that are nearly impossible to win.
Like may others, I used an adhesive but that seal has leaked like a faucet at idle ever since. I have several R2 retainers and the original replacement seal presses in just fine with an appropriate crush fit. If you can push the seal in with your fingers, you have a problem. Otherwise, this is a non-issue and the replacement factory seal you will get with the engine gasket set is OK to use. My 50 and 52 will both get R2 retainers (since I happen to have them) and a standard seal eventually. Otherwise, Phil's solution, developed by Rick Prentice, is the only way to go for old style retainers.