I have a Komatsu PC-50. The hydraulic pilot pump is only a couple of years old. The main hyraulic pump was replaced about 4 months ago. After I replaced the main hydraulic pump it wasn't starting without jump starting. Never had a problem before. I replaced the starter. Still have to jump start it. Also, now once I get it started nothing happens. I changed the fuses and still nothing.
Sounds like it's building pressure while your starting it. Making it hard to turn over.