The jewels are easily replaced so I would not think the red and green jewels would be a problem unless you are grading the 733 as "like new". A concern would be that the some of the early 726 locos had red and green jewels. I wonder if the boiler front was damaged and replaced with improper part. Removing the screw in the top of the smoke box should release the boiler front. Remove it and see if it looks as it has been modified. There should only be a tab at the top. If there is a tab at the bottom or it looks like something was cut off at the bottom, then it is probably the wrong part.