I made the idler more robust by making the hole filled.
From http://www.thingiverse.com/thing:835542 i had to print about 3 Idlers till now because they get weak after some usage.
This is an attempt to prevent this.

No Support material needed (at least not on my printer).
Print at layer height 0.1-0.3, whatever you prefer.
If you are not sure how to use this part, please see the part which this one is a remix from.