Motors will not work under load.

[RcZoNe444]

I have both sealed can and serviceable motors that have problems. The sealed can motor is a Titan 12 turn 550 motor that seams to run fine under no load and as soon as I put the model on the ground the motor stop working. The other motor I have is a Team Orion Pilot 15 turn that runs fine with no load again but as soon as I put the model on the ground it actually seizes up and will not even turn. I have to remove the brushes to free it up and then it spends freely and will run fine again with no load.