how to make my Brother overlocker work properly?

I have a Brother overlocker (4 spools) the number I do not have to hand at the min.

After working perfectly for about four years now (although I do not use it very much) it has started to jam and does not cut the fabric. It just overlocks and makes a strange noise. I have oiled it but it is driving me mad and I continually have to lift the lever and drag out my sewing work. Is it possible to get instructions made into a CD. I have an instruction book and a VHS but no longer have a machine to play it on. HELP!!!!!!!!!!!!!!!!!!!!!!!!