I need to replace a Class 2 power supply.?

Question

The specs are 120v input and 6VDC 150 mA output.

The closest I can find has a 300 mA output. Will it work?

Answer 1

Yes, it will.  The mA rating is the maximum current that the power supply can provide.  If your device only requires 150 mA, it will only draw that much from the 300 mA power supply.  As long as it's 6V output and the plug fits, you should be fine.