||I went thru 3 rebuilts from Four Seasons, and they were great about sending replacements and not charging shipping (I was working directly with them, not a jobber). They all leaked within a day.
When my original one went out I replaced the condenser, the dryer & expansion valve along with the compressor, so I know the system was clean.
Four Season finally sent me a new compressor, new expansion valve and dryer at no additional cost to make things right. I am still using R-12 with a R134 condenser; the R134 condenser has double the amount of rows as the R-12 condenser and boy does it cool a lot better.
My guess is Four Seasons was reusing units that had too much wear on the shaft where the seal goes. Four Seasons is one of, if not the, biggest re-builders in the business. Now Bernie is most likely working with a higher quality re-builder.