Question for M1 Garand guys, please--

Just got a CMP Garand, came in two boxes, stock in one, barrel and other parts in the other.

I assembled the stock and action, but when I tried to install the trigger assembly, could not lock down the trigger guard.
It fits into the action/stock easily, but the guard will not lock, it will not even push down close to the notch.
If the stock is removed, the trigger can be installed and locked into the action without issue.
The trigger can be set into the stock and the guard will easily move into position.
When they are put together, won't lock
Any ideas/suggestions?

Thanks