Your coil should spark everytime that you ground the ground side of the coil when you have 12v to the hot side. That is what the points are doing - making the connection to ground. So, armed with that knowledge you should be able to troubleshoot the electrical side of things. Now as for the spark timing, the retard / advance changes based on engine speed and load - that is what the advance is about. Either one of those is causing you problems. Just fix it. Hell, if a 16 yr old kid can fix his VW bug based on that little bit of knoledge...