OH BOY....
At the risk of paddling even further up the proverbial %*#* creek, I can't let this go since Coach posted such fine examples of the subject. If the question isn't asked, most of us assume everyone has a firm grasp of the details between the concept and the final objective....NOT TRUE. As Coach said, he's a first timer and this may help the rest too.
First of all...take a minute, lay down your components in front of you and contemplate your objective. One if not several solutions should come to mind sooner or later...later is good, it shows you took the time to think about it. Always start with a plan whether its mental or on paper.
Peening the gaps in a gaurd:
*The final objective is to have a DRIVE-ON fit.
*After round one of peening and a re-sand, you may have to do it again until you get that seemless fit on the face. Do whatever it takes.
* Don't overlook the part of the slot under the shoulders. Get it close at least, this will help in the teetering effect before applying the JB Weld...IF you have to use it.
I have to mention here that some us have mills and various needle files and ONLY use a press fit on our guards. If your scribe line for the slot isn't on the guard, chances are you're using the above method. If they're still there, use Dykem or a Sharpy on the tang and keep fitting and filing until you're driving on the last 1/4" or so. While filing, don't be afraid to flare the back of the guard a LITTLE bit. After the press fit, you can fill that gap with JB Weld if needed, but ONLY in the back.
IF using JB-Weld :
*Apply the concoction ONLY to the INSIDE of the guard slot.
*Remove any spill over from the face of the guard BEFORE anything else.
*Lay your guard FACE UP on your vise jaws...slide the tang DOWN INTO the guard.
*Firmly seat the blade shoulders to the guard. You DON'T want any JB under those shoulders.
*Clamp the vise. Leave the thing alone...go play with the kids or dog, take the queen out to dinner. Do anything but fiddle with the thing until tomorrow.
After removing from the vise, you can file/sand off any residue in back of the guard or on the tang. JB is pretty impervious to most cleaners but ZYLENE does work. FOLLOW ALL PRECAUTIONS, ITS NASTY STUFF.
As stated, I don't use this method any more. There's no substitute for a precision fit but I can remember when I had to. Hope this helps and start with a plan.
Rudy