Kavorka:  Is it possible you have reversed the bowed flat spring?  It should only bear on the door (hinge pin cavity) at the spring's center curve.  Also, there is a notch in one end of the spring that is to clear action parts.  The radiused end of the spring goes to the rear and the notched end goes foreward.
  If every thing is clean and lubricated (pipe cleaners work good on door 'hinge pin cavity'), you should be able to hold the magazine door in position against spring pressure and wiggle the hinge pin back into place.  It helps to repeatedly squeeze the door against the spring pressure to align the holes as you wiggle the hinge pin through.
  When fully inserted, rotate the hinge pin so that the  attached flat spring snaps into place even with the receiver bottom.  (Make sure your hinge pin is straight.  Try inserting it through the door while off the rifle.  Try inserting it in the action minus the door and spring.  If it is bent, it can be straitened with a plastic mallet and hardwood block).

I did not take out the carrier with follower attached out of the magazine during the cleaning with cloth and solvent.
The magazine sping is convex and touches the center of the gate.
Does the square end of magazine spring go on top of carrier?
The gate lug  cam just sits below the carrier heel (end)?
I smoothed of end of hinge pin . I was going to put a finishing nail in the rear hinge hole to help with hinge  pin alignment then apply some oil to the hinge  pin hold the gate and start the pin at the front.
I had to use a wooden dowel with light taps to get the hinge pin free when I took it apart for cleaning.
Any more thoughts. Thank you Dave

Can anyone recommend a source to fix my loading gate on my 1898 rifle?
I have tried but cannot get the loading gate open when the hinge pin is in place. I think the pin is bent? I have tried and tried but failed to get it to work.
I have the magazine spring convex curve touching inside center of loading gate, correct placement of magazine ends but no luck.
I need to send it to someone who is knowledgeable.I will pay labor costs  etc.
The gate worked fine until I took it apart for cleaning . I should have left it dirty.
Thank you for your help Iam enclosed my email.
Dave in Michigan
dpaulisin@aol.com

Dave:  A bent hinge pin just makes takedown and reassembly of the Krag magazine door more difficult.  It can be easily straightened.  It is more likely your jammed magazine door is a problem with the magazine spring (either broken or the front tip out of position).  There is an easy check.
  With your Krag barrel and action out of the stock, turn the action so you are looking at the bottom.  Rotate the hinge pin by the small stud/flat-spring toward the magazine door.  This exposes the front tip of the long magazine spring and a cam that is part of the follower/carrier.  The front tip of the magazine spring should be contacting the cam in a small concave notch where it travels as the magazine door is opened and closed.  If the spring tip is outside this notch, the door cannot open.  The only other possibility I can think of is an obstruction to the follower/carrier (debris in the magazine).  If you have the magazine door off, it is very easy to take the follower/carrier out of the action for cleaning.  You simply swing it out the side and pull down.  It is a self-contained unit and can be cleaned and lubricated without further disassembly.

Dave:  Well done you!  I am glad you were able to solve your magazine-door riddle.  The more I play with my Krag rifles and carbines the more I appreciate the cleverness of the designers and the quality of manufacture.