Piano Technology is an interesting profession for those in the music industry who are technically inclined. First and foremost to progress is to have a mentor, rebuilding and service usually requires apprenticeship in a reputable shop. Tuning is also an art form, although the secret like anything is having a perseverance and practice. After learning unisons and octaves then a temperament is needed which is a tuning sequence to cover the tenor area of the piano. Standard tuning time with pitch-raise should be an hour or less, then more time can be spent on action work in the piano during the service call.
If one does not have a mentor, the best solution is to go to a Piano Technology school, i.e. North Bennett School in Boston, Western Ontario University, Chicago School of Piano Technology. This profession is not uncommon for the blind and there is even a school for that at, Emil Fries School of Piano Tuning for the Blind.
A good correspondence course is Randy Potter School of Piano Technology. There are also the tapes of my mentor, Jim Coleman Sr.who has many tapes available, some are included in Randy Potter's course. Mr. Coleman does give private lessons and has trained some of the finest technicians here in the valley of the sun.