It's certainly possible to do your own, if you're handy with engines. Here is an excellent pdf
HOW TO
. You will need Adobe Reader or similar to read the file. It's for a vvc but everything else is the same. It discusses all the issues to be aware of..Finding why the HG failed is vital as simple replacement could result in it going again.
I found it was much better to get Russell to do mine, by the time you buy all the bits and factor in your time and effort involved, it's a no-brainer to have MGRover solutions come and do it Plus you have a guarantee.