Like everything else these days rebuilding injection pumps is not a big business anymore. Most vehicles have unit injectors that are just replaced. Id check with a John Deere, Kubota, Cummins etc dealer and ask the service manage who rebuilds their pumps. The one on your 220 is pretty simple and easily repaired compared to the newer units.
I have a local guy here in Bakersfield that does it called B.E.C.S. that ive had good luck with on all kinds of different pumps as well as injectors.
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