Restoring Grub after cloning a disk

I’ve got a weird one. I’m running VMware ESXi 6.0. I have several virtual Windows servers on it. Two Alma Linux servers and an Alma Linux mail server running Postfix and Dovecot
Something. I suspect a power outage that overran the UPS, happened months ago. We noticed strange things, Let’s Encrypt Certificates stopped renewing. One of the Domain controllers stopped syncing. We were in constant firefighting mode with all the problems.
Quite by accident, I found that the compatibility of all the Linux servers had changed from 8 to 11. Now the VSphere web client doesn’t work on 6.0, but we can’t (money and hardware) move to a newer version, so we tried converter. No good, tried editing the VMX. No good. It’s only the mail server that is kaput. I reinstalled the others.
I set up a new VM Alma box with the exact same spec as the mail server. I attached the blank hard drive to the mail server. (BTW It all loads up and works BUT there is no way we can renew its SSL Certificate - just one of the strange quirks.)
I set up dd to clone the entire drive to the new machine (compatibility 8) and it worked 100% BUT…
It didn’t clone the GRUB so the new cloned drive won’t boot.
I tried AI, but it’s useless because it still doesn’t seem to know what LVM is and I’m STUCK.

Can anyone PLEASE give me a detailed step-by-step (I’m not a Linux guru) instruction for restoring the GRUB once the dd clone is completed?
telling me to mount this and the do that ain’t going to help. I’m 83 and past my Novell days and I need the commands. the old disk is sda and the new one sdb.