Door works manually with no problem
It is unusual to need to change a motor start capacitor. Mostly it is age and poor quality that causes them to fail. In a case where the capacitor is a combination start and run capacitor, the run section is rather more highly stressed and low quality, wrong specification or a motor fault is more likely to cause capacitor failure.
If you are certain the correct capacitor has been used as replacements I suggest you suspect a motor fault, perhaps a few shorted turns in the run windings. Checking the current drawn by the motor should give an indication.
Testimonial: "The old capacitors are 330v 32-40 MFD and I have put 45-57 MFD( 220-250v). When the door opens the motor current is 2.5A and sometimes 3.0A. Its a bit high but I am not 100% sure that my digital clamp meter is that accurate"
The wrong capacitors could be your problem. While the capacity value is not super-critical due to the wide tolerance on that type of capacitor it would be best to replace with Identical values. It is the working voltage that is suspected. A capacitor designed to work with alternating mains current will be marked as such and that means it will tolerate a much higher peak voltage. The stated voltage of your ac mains is an average or rms value. The peak voltage is much higher. The calculations are complex and beyond me but I happen to know the peak value of a 240 volt rms 50Hz ac mains supply is 327 volts and considering we are using it with a switched inductive load there can be transient voltages present that are much higher than that.
It is important to use a capacitor specifically marked as suitable for ac or if a general purpose capacitor is being used because of desperation the working voltage chosen should be as close to double the supply voltage as possible. Usually it is best to source a direct replacement either as a spare part from the manufacturer of the motor or from the manufacturer of the capacitor which often would be much, much cheaper.
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did you replace the capacitors and then they burnt out . Where are the capacitors are they electrolytic capacitors and what voltage rating where they and what voltage is the garage door designed to run on. wondering if it is a 110 volt door like US ?
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