[Half-Inch Stud]

3 possibilities:

1. Starter is mounted to a painted block pad. Overall starter case assy, GND path & wiring experiencing a resistive path.

2. Duh yea, internal slug-wall friction gone high when warm...put a torque wrench onto the harmonic balancer, or

if your "feeling lucky" grab the balancer pulley by hand and see if you can turn the assy by hand cold, then hot. I do this on my assys (takes grip, concentration and technique ( I pull the Left-side V-belt too, push the right side down)

3. Bearing damage in crank,cam, maybe rods.

take your pick...I had #3 occur because I puts STD bearings on a .010 crank...you'd never dooo thaaat right.