Water Seepage in Basement after Heavy Rain

I own a ranch-style home that was built in the '50s. The basement is about 7 1/2 ft deep with cinderblock walls. When we moved in 7 years ago, every time it rained, water would come into the basement and run to drains in the floors. Outside, our drain spouts were directed into vertical terracotta drains. I dug down about 18", connected the drains to PVC, and ran the drains away from the house.

Problem solved, right? Not so fast. Now about twice a year after a heavy rain, I still get slight seepage into my basement. It only comes in a one spot along a wall, and it only ever runs about 1-2 feet into the room. It always appears to be trickling in from a mortar joint about 18" up the wall. I have opened the mortar joint and filled with hydraulic cement. I also painted all the walls with UGL DryLok. The water stills seeps through after a heavy rain. I want to finish my basement but can't with the moisture problem.

There is a window well about 4 feet away. There is a visible crack in the mortar in the topmost cinderblock at the base of the window. Is that a likely culprit? The water would have to travel diagonally down and across appearing near the floor of the basement.

Do I have to dig down to the foundation and waterproof the whole side from the outside? I hope not. I'm also concerned that the terracotta drain around the perimeter of the foundation could be crushed or filled with debris. Should I just reopen to mortar joint and try again with the hydraulic cement? I want to do the easiest thing, but I also need a permanent fix.

Thanks. :)

Water Seepage in Basement after Heavy Rain