Temperamental Window

[mboucher70 at hotmail.com]

One day, the passenger side power window just decided it wasn't going to come up.  

Buttons were pressed and pressed, fuses were checked, window glass was rocked back and forth, to no avail.  Then, at a moment of her choosing, she decided to let me put her window up.

I forgot about it, and it happened again.  Had to start remembering to warn people not to bring that window down.

The window doesn't ever seem to fail to go down.  But 'up' is very temperamental.  However, when it goes up or down, it does so quite normally, that is, its not slow and nothing is making a strange noise, as to indicate a worn out motor or something rubbing or stuck.

I've heard that power window 'regulators' are notoriously unreliable on BMW's.  But in this case, since its intermittent, I'm wondering if the cause might be something else.  First thought is a connection.  Second thought is a relay.  Any suggestions on which or where to check?

Thanks

Charles