1946 Lionel 726M-1 High Stack Motor Question

In Bob Hannon's book "O-Gauge Reference Manual I" there is a little information on the large stack motor.  He indicate the length of the armature from the pinion end to the face of the commutator should be 3.352". From the thrust face at the bottom of the laminations to the face of the commutator he shows as 1 1/8". That last number would be the important number, but you can not get to it to check it without pulling the pinion off the shaft and removing the armature from the motor.   He shows the length of the lamination stack as 25/32". 

Im really trying to avoid pulling that gear. Thanks for the info. 

The spur gear motors that I've seen usually don't have a problem with thrust forces pushing the armature against the brush plate or the opposite bearing.
How do things look if you run the motor?
Are the armature windings centered in the field?

Thanks for the replies. To answer the last question, no, the armature is not centered in the field. One layer of lamination sticks out past the field. I put it all back together and it runs like a watch. I will post a pic of the motor tomorrow. 

 I cannot see how this would happen unless washers were placed in between the bearing and armature. I took a dental pic and probed around in there and there are no thrust washers. Best guess is somehow it was made that way. I tried to put an NOS red brush plate I had on it for looks. The red plate has staked on brush tubes and they hit the armature face. I could not even tighten the screw down.....Odd issue, but unless I want to send it out i suppose I need to live with it. Either way the loco is a super runner. I was always told these 46' berks were difficult to tune and poor runners, but this one is superb! 

 Either way the loco is a super runner. I was always told these 46' berks were difficult to tune and poor runners, but this one is superb! 

Sounds like a previous owner did a nice tune-up and shimmed everything properly. If it were mine, I'd leave the work alone, and just lubricate it.

 I cannot see how this would happen unless washers were placed in between the bearing and armature.

There is an Oilite bearing pressed into each end of the motor housing. As I recall, there are no stops in the casting to control how far those bearing get pressed in. Maybe the bearing that is closest to the armature head isn't pressed in that deeply.

As I already posted, if the engine is running well, and nothing is hitting, I would leave it alone.

All the shims were removed and it runs perfectly now. I suppose they were in there for a reason. Prior to their removal it ran but was power hungry and the driveline was very tight. I have no plans to mess with the motor. Thanks again for your help.