fried esc or motor?

[w824gb3]

We've been running my lads rtr mad rat on a 2s lipo. Recently the car is a lot slower than it used to be. There are no mechanical issues and I know the lipo Is good so its either motor or esc. If I get my volt meter on the battery I have 8.8v. If I put the car on full power I am only seeing 7.4v at the motor terminals. Is a 1.4v drop through the esc normal or have we cooked it?