Retina MBP adapter not working

[zamboknee]

How do I tell if my power adapter is not working?
Here's the twist: I'm using a power adapter from a 2009 MBP with my 2015 Retina MBP by way of the plug adapter.
It had been working fine but recently it would only intermittently charge the laptop (no light on adapter, no charging in menu).
I cleaned the contacts (plugs and receptacle) with rubbing alcohol but it seems to be a bigger issue than 'grime on the contacts'.
I'll buy a new adapter if I have to I guess I just want to find the cheapest way to fix this before that option.
Thanks

 

[iMacDragon]

Easiest way really would be finding someone else's laptop to test the adapter against too.

 

[zamboknee]

Yeah, plugged it into my coworker's Air and it didn't work there.

 

[zamboknee]

swapped out the converter (the thing that converts an older magsafe to the newer size) to one that I don't use as often and it seems to be charging fine now.
So new converter I guess?