Downgrading from Modaco 3.2 custom ROM

[Guest Mocoddage]

Hi there. I'm tearing my hair out at this point, so any help would be greatly appreciated.

I'm running Modaco's 3.2 ROM on a rooted Telus Hero, and heard out that if I downgrade to the 2.73.405.5 build, it will prompt to upgrade to Android 2.1. But when I run the RUU, I get:

ERROR [132]: SIGNATURE ERROR

I did a factory reset and formatted my SD card, then redid the Goldcard procedure, but I keep getting the same error. Anybody know how to downgrade from the Modaco ROM?

Thanks in advance.