Dan, the dive brake were to be extended before the dive began. If they were extend once the dive had begun then there was the possibility of them not extended equally.
In the MTO, the A-36s were in such demand to fly missions that proper maintainance of the a/c could not be done. It would have been much easier to disable the hydraulic lines that operated the dive brakes.
@ oldman,
if the much lighter A-36 required dive brakes to keep it dive speed under 390mph, how did the P-47 keep its speed down? Level, the P-47 would do over 400kph so what would it be doing in a FULL power vertical, or near vertical, dive? The P-47 would descending at an angle near to which the Spit did, that is 60*, which is not dive bombing.
Who took the time to read the thread in the link I posted?