Your method of testing the belts are fine, the alt belts can be tricky as you need to loosen, IIRC, there are three bolts, one of which is the adjusting bolt itself. The way I did this was from under the car the 17mm, I think, bolt (no nut on this one, as it threads into the bracket) near bottom outside of alt. Then in front near engine there is another 17mm bolt with nut, I put an open end wrench on the back side, and a socket on the front end, you need to move the fan around a bit, this is the bolt I bent my ratchet on, loosen. Then the nut on the back end of the "L" adjuster bolt, this allows you to use a 13mm socket on the long nut lookin' thing. The only way I know of to check crank pulley, would be to remove all belts, or tighten down the bolts holding it on, try to anyway, if they don't budge, should be OK. Hope this helps.

__________________
83 SD

84 CD