I have an old but always working 128 Husqvarna. So finally stopped working. I put a new carburetor, gas tank, and now replace the cylinder and piston. The reason was I measured the compression and it read 50 psi, so I replaced the piston and cylinder thinking it was to low. After all the changes the pressures is the same at 50 psi on new piston and new cylinder. And of course wouldn't start. I know for the money I could already buy a new one already, but I just want to fix this one. Any one please can tell me what it should be the compression for this model??? Thanks