Air Condition Clutch won't engage properly

The air conditioning on my 98 Civic won't come on most of the time. I have power to the clutch but it won't pull in until I use a screwdriver to spin it or pry on the armature plate. Then it suddenly snaps in and the A/C works until it is switched off.
The field winding resistance seems to measure a bit less than the specified 3.05 to 3.35 ohms (I measured from the relay terminal to ground and got 6 ohms. Then I subtracted the approximately 3.5 ohms of my test leads.
The clearance between the rotor pulley and the armature plate seems to be on the high side of the tolerance, about 0.6mm (should be 0.5mm +/- 0.15mm).
I haven't removed the compressor and was hoping to get away with a repair that didn't require removal.
Any ideas about where the problem might be and how to do a repair?

Mine, on a '95 Civic, would not pull in at all. Even if I applied 12 volts straight to the clutch. I ended up replacing the clutch to fix it. On the '95 you can replace the clutch without removing the compressor. I had to remove the compressor mounting bolts to move it to a position where I could reach everything, but I was able to do that without disconnecting the refrigerant lines.

If you haven't already done this, you might test the clutch by disconnecting it from everything else including whatever thermal protector your compressor has. Then you can connect 12V directly to the clutch coil. Be careful that you don't let your positive lead touch anything else. Only connect the power momentarily. The clutch should pull in. If it does, the problem could be high resistance in the relay or the thermal protector.

Otherwise, I don't know what it might be.

Mine, on a '95 Civic, would not pull in at all. Even if I applied 12 volts straight to the clutch. I ended up replacing the clutch to fix it. On the '95 you can replace the clutch without removing the compressor. I had to remove the compressor mounting bolts to move it to a position where I could reach everything, but I was able to do that without disconnecting the refrigerant lines.

If you haven't already done this, you might test the clutch by disconnecting it from everything else including whatever thermal protector your compressor has. Then you can connect 12V directly to the clutch coil. Be careful that you don't let your positive lead touch anything else. Only connect the power momentarily. The clutch should pull in. If it does, the problem could be high resistance in the relay or the thermal protector.

Otherwise, I don't know what it might be.
Thanks. I'll try and by-pass the thermal protector like you suggest. I tried cleaning the clutch by blowing some air through the gap and thought that helped. It pulled in a couple of times and then no more.
Looks like I'll have to unbolt and move the power steering pump and reservoir to get at the compressor. Did you need to do that also?

No, but mine is a 1995, and is probably different than yours. I removed the left front wheel, loosened the plastic fender liner, and reached the compressor through the wheel well. It wasn't too bad that way. And I had to remove the plastic splash shield that is underneath the front of the car and spans from the left side to the right side, but that's not too hard either on my car.