Vintage Synth Repair

Hi all, I've got a simple question for a simple problem.

unit: boss dr 770 drum machine

problem: 1 of 3 prongs holding the 14v ac plug housing (inside the 
unit itself) to the main circuit board has broken its solder (mearly 
separated actually).  If I plug the unit in and apply pressure 
laterally to where the power supply plugs into the unit, it will 
restore contact and turn the unit on, but as soon as pressure is 
released, it loses power and shuts off.

It would cost $25 to have it fixed in town, and I don't have that 
kind of money at the moment for anything other than food.  I have a 
solder pen and some non-lead flux.  I've successfully assembled a big 
briar etherwave theremin kit.  Do I have the skill needed to fix this 
problem myself?  The original solder of the broken point is so tidy, 
will I be able to make a new connection as secure and safe as the 
old?  Do I have to de-solder first - or just re-solder?

I can even scan in the broken solder point and e-mail a picture of it 
if this would help.  I just really need to save money wherever 
possible.

Any help would be VERY much appreciated.

thanks in advance guys - I wanna nail this repair job the first time.

-pk