This may be a silly question, but how do you replace the rubber ends on the hard plastic vacuum lines? I had one come apart and the rubber vacuum hose I have (Volvo original) fits the manifold fitting perfectly but is to large an ID to grip the hard plastic vacuum line. I know I can just replace the whole line with rubber, but I wanted to keep the plastic line since it is the one that goes to the ignition module (routes under the engine). Let me know what your repair hints are. Thanks.