Compressor not starting all the time

Hi,
I would like to get the part number that can give a boost to start the compressor. I had Sears 4 My Home diagnose the problem, and the tech said a new compressor/condensor was needed to the tune of $750. That’s not happening on a 9 year old unit that can be purchased for $900 at Home Depot. He did offer that there was a device that would start the compressor in this situation, but that ultimately the compressor will fail. He gave me the part number HS42, but I haven’t been able to find it. I replaced the overload/relay/capacitor a little over a year ago, and after the buzzing returned, I did it again last month with success that lasted about a week before the buzzing/not starting returned. Oddly enough, disconnecting and reconnecting power starts the compressor 80% of the time, and the old relay still works, just not as well as the new one.

The compressor is warm to the touch when running and for quite awhile after it shuts off, but I wouldn’t rate it as hot.

The unit still cools, so I’m thinking I’ll give this a try to see how long I can delay getting a new one.

Now I just need to know if it’s possible and what I need/have to do.

Thanks.