You can get resistors and capacitors at almost any electronics place.
I frequently use justradios.com (he is in canada).
The electrolytic (lytic) capacitors have a PLUS and MINUS side, so you need to be careful when reinstalling them.
They also come in radial (wires come out same side of tube) and axial wires come out different sides.
The voltage of a replacement cap must be the same OR larger than the original voltage, and the capacitance should be as close
as possible to the original (if same capacitance is not available, use the next highest value). Lytics also tend to go bad especially if not used for
a while. I would recommend you replace them even if they are good, DISCHARGE CAPACITORS BEFORE TOUCHING THE LEADS.
Resistors have to give some sort of value. Looking at the schematic, the value you get can read at the correct value or lower - you need to remove
at least 1 side to test accurately. You need to use the same wattage OR larger, and the same resistance value. Look for discolored sections of the PCB or resistors - that indicates too much heat, and that could cause a resistor to go bad quickly. Resistors change value with age, but most of
the time it will still be in tolerance.
Check physical size of components if you go to a larger wattage or larger voltage or capacitance.
If you need other help, please contact me.