But basically it does not matter whether you decide to use a polarized electrolytic or a non-polar capacitor.
What matters is that you replace the old capacitor with a new one of similar value capacitance and voltage rating.

So for instance if your equipment used 4 uf @ 300vdc electrolytic caps... you do not need to replace them specifically with electrolytic caps... you can just replace it with ANY 4 uf @ 300-400vdc

If you ever find a non-polar, non-electrolytic cap in a DC circuit area (such as a power supply filter)....you could replace it with a polarized electrolytic cap.. you just need to place the positive terminal in the most positive part of the circuit.... such as the cathode of the rectifier.

So any cap can usually replace any other cap as long as the size and voltage are appropriate... and when using electrolytics.. just observe proper polarity.