Hi
Retufting can be very successful, and save the client or insurer alot of money on replacement. If retufting then I agree that the primary backing needs to be intact for you to anchor the tufts in to, but there are other ways to skin a cat if the primary backing has been damaged.
I have found the use of a hot melt glue gun an essential part of my carpet repair kit. The hot melt glue can be very useful in dealing with deeper burn damaged carpet and secures the tufts probably stronger than the original tufts.
Many of the impliments within a manacure set can be extremely useful to in manipulating fibres.
You are absolutely right though Woodman it takes practice, and it is not advisable to let yourself loose on a customers carpet until you are confident.
I went on a carpet repair course put on by the National Carpet Cleaners Association many years ago, which was tutored by Barry Pierce of Leicester, which was excellent. Might be worthwhile enquiring whether they plan to do any more courses.
Kind regards
Robert