A friend of mine was given a used Stihl FS 76 straight shaft trimmer a few years ago by his neighbor. Now, my friend has decided he would like to get the trimmer running again. Being that his strengths lie with automobile/bus repair, he put a trimmer new trimmer head on it the last time he ran it several years ago and forgot to put the washer on in between the head and the gearbox. Well, he ended up seizing up the driveshaft because the head spun down against the gearbox all the way and he wanted me to see if I could get it off. I managed to remove the gearbox from the shaft and stick a screwdriver down into the socket inside and twist...sure enough the head broke loose and I unscrewed it off then put the gearbox back onto the shaft. He now knows to put the washer on there first THEN screw the head on Best he can tell, the engine still has sufficient compression and he's going to try to get it to run this weekend and let me know what happens...or not, whatever the case maybe. At any rate, he'll need a new head and a new guard for sure. My question here is, does anyone have any general information about the FS 76? What is the displacement of the engine? Spark plug size? [Looking at it I think it's a CJ8 type plug] What about just general comments about the unit - how durable is it, anything that he must be aware of, etc? I tried doing a Google search on the FS 76 and came upon a bunch of vendors selling parts for it but no real information/feedback on the trimmer itself. Overall, the unit looks very clean and in general excellent shape for being as old as it is. Thanks in advance.