Most of my training has been through OJT with other technicians & going through the repair seminars at scuba trade shows like DEMA. Be aware, those seminars are rather expensive (IMO) running $100- $300 each typically, depending on the manufacturer & the equipment you expect to work on. Also be aware that some manufacturers like ScubaPro, Aqualung & such, you must typically have a dealership sponsorship to get into the seminars, to the best of my knowledge. Are there ways to circumvent this? I suppose, there probably is. I am not familiar with that.