Pro copter , motor just twitches and judders

[butmuncher]

Hi,
Just had a mate round that has just got into heli's, he has a pro copter 450 type heli and the motor just twitches when throttle is added and does'nt actually spin or do anything, esc gets a wee warm.
I have no clue, anybody have ideas to what he needs.
I'd say esc but i do'nt really know much but i can fly /

[glen_j]

check the bullet connectors on the motor/esc, a loose connection could cause this

[butmuncher]

check the bullet connectors on the motor/esc, a loose connection could cause this

Thanks i'll let him know now, fingers crossed