You might check if the clutch has an adjustment for the diameter of the halyard. If you are too small diameter you max out your holding power but you can seperate the cover and core due to the pressure at the clutch point. If you can back up to the proper diameter the clutch should hold without blowing up the line.
I know Spinlock jammers have this adjustment (don't ask how I know)

Somewhat different solution we used the large harken cam cleats for the spin halyard on Tornado's and had this problem. (Same problem as you experience... the cover and core would blow up) We would use two cam cleats inline. especially when we doubled the loads with a 1 to 2 halyard system. Perhaps this is a solution.