I've checked on this and this is what I found.

The original power supply is proving 5V - 2A, +12V - 0.3A, -12V - 0.2A
While the replacement power supply 5V - 4A, +12V - 2A, -12V - 0.5A

Has the common ground of the +12V and +5V effect on the -12V in anyway?