TP1507 is under the FireWire board, just beside the mounting hole above U601, or baout an inch above the CPU.
C1520 is partially covered by the left hand audio board ribbon. You'll not get to its pins without removing the motherboard, but you could try the right-hand pin of the inductior (L1501( close to that ribbon.
The voltage across the replaced cap is no good – it needs to be at least 18-20V. This is why the voltage across C1514 is too low (it needs to be solid 15V). Given this, the other voltages don't matter.
I think you'll have to send it in. Sorry.
