I am having problems with Bachmann EZ Track.  The track itself is fine except for having to file the rail tops at the joints for smooth running.  What I am having a problem with a model 44440, 30 degree crossing which I bought just yesterday.  It fit perfectly into my small layout.  Then I gathered all of my locomotives to test how they would run through the crossing. . . . .  They don't - happily.  I expected that there might be problems with short wheel base (0-4-0 and 0-6-0) switchers.  However, my 4-6-2 Pacific and my GP-20 have problems also.  The problem is either partial or complete stalling, especially at slow scale speeds.  In addition to the stalling, the engines tend to hop and derail about every second or third pass.  Since the crossing fits so well in my track plan, I don't want to return it.  I would like to fix it if possible.  Someone suggested that the frogs might be too shallow and that the wheel flanges may be bottoming out as the loco passes through. Can you help?       Sequimbill