I bought a used echo srm-3000 and it had a manual feed head on it. For the sake of time I wanted to put a bump head on it. So I bought an echomatic head that says it fits the srm-3000 and many others. However, the threads in the head are bigger than the threads on the shaft coming out of the trimmer. The head did not come with any adaptors and I am curious if there is a trick to make this work.