</font><font color="blue" class="small">( I How easy is it to install a new one? )</font>
DF owners who have done what you're asking are possibly going to be in short supply. So I'm composing this response with the assumption that your DF tach sensor operates the same as those on my KAMA and two previous Jinmas.
This procedure is done with the engine not running. Once the conductor wire is disconnected from the sensor, there should be a lock nut on the sensor threads. Loosen it, then remove the sensor from the bell housing. Clean the opening if necessary. Screw in the replacement sensor till you feel the tip touch the flywheel. Back it out about 3/4 turn. Pull the compression release, and - with a socket wrench on the timing pulley - slowly rotate the crankshaft a full 360 degrees. When you've confirmed that the flywheel teeth will not strike the new sensor, tighten the lock nut and connect the sensor wire. Start engine, check tach for proper operation. Some fine tuning of sensor tip distance from flywheel teeth may be necessary if the tach action is erratic.
//greg//
