I have a 1990, Force 120HP, L-Drive motor. I just bought a brand new battery. When I turn the key the motor cranks so slow, it's not even close to turning over. I used jumper cables and bypassed the solenoid switch and battery cable. Same thing happened. When I remove the spark plugs, it turnes over fine. As I install each plug the cranking speed reduces. Could my starter be unable to produce enough torque to turn the engine with all plugs (full compression), but OK with the plugs removed (no compression)?