Hi, I have a Masport 550st multicatch in meed of 4 new blades but no one around here can tell me what blades it needs without pulling the old ones off and taking them in. I could go back to where I bought it but that is on the other side of Canberra. I have one other problem with it. It doesn't seen to be getting full rev's on full throttle there is no difference between full & half throttle I took it back to where I bought it from they said it was working fine. Any suggestions?