https://www.lionelsupport.com/...;submitButton=Search
Copy and paste into your browser. Lionel, parts diagram for that engine.
That part riveted.
This MIGHT be possible.. But, once the clips are removed on the T-BAR . The T-BAR will have to be able to be moved high enough to let the coupler slide out. This may allow access to the solder joint. Getting the T-bar back in and the coupler back in place you might some brain power
1) Remove C clip under T bar holding coupler. Remove spring and washers and note their order. See if t bar goes high enough to release the coupler
and allow access to the solder joint. If this works, You might have to use a little brain power getting using something to put pressure on the top of
the T-Bar
2) The proper way! Remove the shell. Remove the truck. Remove the t-bar. You should definitely be able to gain access to the joint without totally
removing the coupler. Or you can remove it.