Fully agree with Stewart. I've done this twice in my career: in both cases it was a step down both in role and salary but both allowed me to very effectively bypass a "road block" in the previous company. BUT (using hindsight) both times the companies involved identified at interview that I would have potential to grow in their company, and that they were interested in that, otherwise they would probably not have offered me the job. A company that just wants a technician will probably see you as a risk: yes you could do the job, but you would get bored and leave. The company you want is one that sees this as an opportunity to get someone in to solve an immediate staff shortage well, but with the opportunity to take on more as time allows.
So, be clear in your application that you are looking for an opportunity to learn new skills from the ground up, and don't undersell yourself otherwise you could be offered a really dead end job.
Hope all goes well,
Andy Millar CEng MIET CMgr MCMIhttp://www.linkedin.com/in/millarandy
"The aim of argument, or of discussion, should not be victory, but progress." Joseph Joubert