This morning I went and took the backstay adjuster to see if it can be fixed. In the past we have used Ernie Redford of Redford Engineering in Osborne Park for work like this. Parts for this equipment are not available anymore, and so any parts that are required need to be fabricated. Ernie had a quick look at it, and I helped him pull it apart to find the problem, and it looks as though the gear that threads onto the stainless steel shaft coming off the actual backstay itself is worn/stripped. We attempted to get it off, but ran out of time as I needed to get to work. Ernie said he would look at it to see what he could do. If he has to make a new cog for it, it will be expensive time consuming and thus expensive, however if he is able to retrofit a new thread into it then it might be "easier".
In the meantime I will do a little bit more research to see how much a new one will cost. Looks like the best/cheapest option is getting it in from the US.