Dave at Recommended service tore me a new one for pounding on the crank sprocket on my /5. To take it off, a good puller is vital. A special one for that job is about $100. Same with the cam sprocket. Replace both while you are at it, otherwise the chain will wear quickly and be exactly where it was before. To put it on, put the crank and front bearing case in the freezer overnight. (ideally the whole engine) Or outside in the cold will do. Put the bearing and the sprocket in the oven to 400*. They should drop on, without any resistance.
The bottom sprocket needs its endplay adjusted to +/- .001, as well as a special tool and a press. Just pull the cam and take it somewhere. Takes them 30 minutes.