Hello everybody, I am somehow a beginner in working with oscilloscopes, and I bought my self an old 50MHz Philips PM3240 scope. Everything seems to work fine except time base. The knob doesn't seem to respond no matter the settings. If I select to use eternal x deflect, then there are two dots on screen (representing the calibrating signal). I can also get two horizontal lines one upon the other representing calibration signal on one setting, not rely shore on witch right now, but at least I know the screen is working, but I can't "zoom in" to the signal. I don't know where to start, I looked at all of the capacitors and all seem to be fine, looked the connectors and switches but can't seem to find the right spot. Can anyone point me in the right direction please?