Will the N&W class J 4-8-4, perform well on Bachmann E-ZTrack 11.25 radius track?

 For several days now, When I click on "Mark items read", i get the following error:
"Session Verification Failed. Please log out and back in again and then try again"
When i click on "logout" I get the same error.
If I clear cookies the problem goes away for while but then when i come back to this forum the problem starts all over again.
Any one else having this problem?

Steam engine is a Northern 4-8-4 with Vanderbuilt tender. Seems this problem just started recently:
When the engine is moving on a curved section of track the rear of the engine fishtails. That is it moves from side to side and the motion is very noticeable.
Any ideas on what could be causing this fishtailing motion?
Thanks

 I have purchased several N-Scale Bachmann assembled buildings which include various automobiles. Anyone know of a place where cars of this type can be purchased. I want to populate my parking lots and train station with cars and not spend a small fortune doing so.
Thanks

  I decided to check the wheels of both the engine and tender with the gauge.
All of the wheel distances had to be adjusted outward acording to the gauge. After I finished adjusting and proceded to test the performance the tender would not stay on the tracks.
The Ez-track seems to be in adjustment acording to the nmra gauge. So i then decreased the wheel distances of the tender which has 8 wheels per truck and the tender stopped jumping the track. This was occuring anywhere on the layout. In fact the rerailer would cause the wheels to derail.
Any one have an explanation?
One other thing adjusting the wheels of the engine seems to have stopped the engine hunting problem.

I have 2 Bachmann Steam Engines that I want to convert from rapido:
1. Northern 4-8-4 w/ Vanderbilt tender
2. Northern 4-8-4 w/ Tender (not specified) came in the Empire builder set.
For 1. MT chart lists 3 couplers:
1128 (001 30 012)
1129 (001 30 013)
1130 (001 30 014)
For #2. MT lists 1133 (001 30 012)
3 questions For someone who had done the conversion.
How do you know which of the 3 for 1 to use?
What are the numbers in the Parens. for?
What conversion number would i use for the rolling stock?