Cable and pedistal
You may have already checked this, but disconnect the cable from the trans and try moving the lever, if it moves freely then its not the cable. This could save you from removing the compass. I have an Edson pedistal on my '84 C30 and my levers were stiff, surveyour said they needed replacing, PO said he liked them stiff. This was not the case, the delrin bushing at the lever needed replacing. Edson said they tend to swell up after years of mixing with salt air.After verifying it is not the trans, remove the compass and binnicle. You will find the cable connection to the lever. Remove the clevis pin and move the lever, if stiff it should be the bushing, next try to move the cable, still disconnected from the trans. You will have found the problem by now. While you have access, check the throttle, you do not have to disconnect from the engine to test.As I said, I have an Edson so my comments will be directed towards this type. There will be an acor nut on the aft side of the pedistal about midway between the wheel and floor, this supports a bracket that holds both cables in place. With both cables disconnected from the levers, trans and engine, slowly pull them up to release the bracket. Use a messenger line and replace the cable(s).I was lucky and only needed the throttle bushing. It is not a difficult job.