Pulling Old Wires

I purchased (see below) a light with 100 feet of cable and LED bulb to replace the corroded fixture in our forty year old Anthony Pool. I have taken the light out of the pool, which is at the deep end.  I have removed the wires from the light switch, that I am replacing with a GFCI switch. I have removed the wires from the breaker box and the three wires extend from the conduit and are free to be pulled. I can not get the wires to move at all.  The run is about 52 feet from the niche which starts at about 4 feet down in the deep endand is likely 90 degrees at the niche to the 90 degree turn at the corner of the pool to a possible 90 degree turn up to the surface and the breaker box. This is worst case senario. All I can tell you is the wires go out the back of the niche and the conduit comes out of the ground vertically.

I have seen videos on line and know how to pull wires with and without a fish. I know there is lubricant to run new wires. One blog said to try water till no debris comes out and then pulll the wires and then blow the conduit dry. I need any advise you can give give me, a DYIer, short of hiring a professional and or replacing the conduit

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