I have changed more compressors then cap tubes as well. More then half those compressors were not a cap tube system. Poe oil and cape tubes don't seem to play well. Maybe 10% of the epuipment owners i know keep there coils clean. High temperatures and poe oil make a bad mix. I find on fractional horsepower compressors most failures are do to pluged cap tubes. I see it as cheap insurance on these compressor change outs.