I have a lift master garage door opener model 1050 6.How can I determine if the transmitter or the operator itself is bad? It will operate with the button but not with the remote. Has new batteries.

SOURCE: Lift-Master garage door opener Model 1045-6 1/3 hp

There is a thermal cut out in the motor, usually the motor must cool before the opener will operate again. If the opener only operates 3 times it must be heating up too quickly.
First you opener is only made to do your job for you, which is opening and closing the door. If the door does not operate properly manually the opener will not operate properly.
When the door is disconnected from the opener it should lift easilly, it should basically stay at whatever point you let go of it (midway and fully open) and it should close without slamming down. It does not matter what size the door is!!! If it does not something is wrong with your springs and the door can be VERY DANGEROUS!!
With that being said it sounds more like a static lock-up possibly a loose ground or even a circuit problem in the home.
Bryan

SOURCE: remotes quit working for garage door

I had the same problem with my Craftsman opener but different model. However to fix this I simply followed the instructions that came with the opener and reprogramed the remote to the opener. The instructions are in your owners manual and are pretty straight forward.. John

SOURCE: Remote will not operate garage door opener from outside garage

Will the remotes work in the garage? If yes but not outside with the door closed you might have radio interferace with your remotes. You might have to chage to a your reciever and remotes to a different brand (frequency). Sometimes it is less trouble to change out the operator. Chamerlain changed frequency from 390 (old) to 315 (new). 

SOURCE: Remote Entry System not working, 05 Chrysler T&C

there is an update foe the body control module that will generally fix the problem. you will ned to take it to the dealer to have it done.

SOURCE: keypad garage door opener will not operate

what keypad are you using with new opener? Frequency has changed. can't use old one. you probably never needed to change things; just needed to follow proper coding procedures.