My Mac G4 (mirror doors) works fine and I appreciate it. Lately, the machine is difficult to turn on. I press the button, the light briefly flashes, nothing happens. I pull out the power cord from the socket, put it back in, press the button, the light briefly flashes, nothing else happens. I go through this process several times (in about 30 minutes), and finally the Mac starts and other than the date and time must be reset, everything works as normal. For 2-3 days the Mac will turn on without problems. But then again, it becomes difficult. The battery is about 10 months old. I suspect it's the power supply. The local Mac authority shop will not do it, because Apple no longer makes power supplies for my vintage Mac. Trouble-shooting and repairing Mac problems are new to me. I found a supplier that sells the required power supply for $250. Before buying I'd like to make sure that is the problem. I appreciate all help, suggestions, and advice.