We have a CIH685 that has given us a few similar problems occasionally and fortunately, it was never too serious. Like BMr, a couple of times it was just a matter of reattaching the solenoid wire at the back of the FWD drive train. It seems to be in a fairly exposed place and we do use our tractor in the bush a bit so it has gotten torn off on brush.
We have also had to replace the splined coupler right behind the front differential a couple of times. That cost about $150 +/- for the coupler and about 1/2 hr. to change it. Maybe 1 hr. In the winter! :wink:
The last time we changed it, I thought we might have to replace the input shaft into the front differential. Ow. Ow ow ow ow ouch. That was going to be almost 3 grand. But we discovered that the bushings that the front axle rocks on were worn badly and that was allowing the front axle to tip backward and forward enough that it was ripping the splines out of the coupler.
I guess those grease fittings on the axle bushings are there for a reason.
The trick is to take the shield off to expose the drive shaft and try to see where the slippage is. If it is the front splined couple, it will be hard to see whether the input shaft is turning because the coupler runs so close to the differential housing. Don't drive over yourself or somebody else when doing all this!!!!
Maybe the best and safest way to check the couplers is to just take them off and do a visual. It is not a really big job, just remove the shield and pull the 4 bolts out of both couplers and slide the shaft endways far enough to drop one end out and then slide it the other way to get it off the other end. Presto.
Or in our cold, wintery weather it would be more like preeeeeeeessssssssstttoooooo.
