Problem with AM 9015 motor

[ferrari77]

Hi guys

I have an AM 9015 motor that I am running from a 12v power supply
when I turn it on, it spikes and draws around 1.5 amps and then settles to 1.2 amps like the free current specs say
usually when I run it, it spikes to 1.5A and then runs for a .5-3 seconds and then stops, I can see the fan in the back twitching but it won't turn (happens in both directions)
other times it won't start at all and turning the motor a few degrees causes it to repeat the symptoms above (run for a bit then stop and twitch)

all of this happens without a gearbox attached but when I attach a versaplanetary 10:1 the issue is the same

my initial thoughts are it is not getting enough current or the wire is too small to give it enough current (20 AWG) but according to the power supply it is not trying to draw much more current so that is confusing me

any ideas on why this is happening? thanks