Chain tensioner stuck fast wont move anti or clocwise

Try a specific oil like 3-IN-ONE® Fast-Acting Penetrant
Patience, may best to wait overnight or days to prevent over powering, breaking a bolt.

There are many penetrating oils
breaks apart tough bonds, and is better than the competition in preventing new rust from forming. 3-IN-ONE Fast-Acting Penetrant is safe to use on metal, plastic, and rubber, and the twist-tip Marksman Spout ensures precise, no-mess and leak-free application, so you can get unstuck easily without all the mess.USE FORFreeing stuck and rusted bolts, nuts, hinges, threads, and chains
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Penetrating oil may help, use AG-10 if you can get it. Tap the frozen part with a hammer, a rawhide one if possible, for 1 minute while attempting to wiggle the part. If you get it out, file the mating surfaces and coat with an anti-sieze compound such as Never-Seez before you reassemble it.

Try 'break free' or any kind of penetrating spray around the throttle. Give it 15 min to soak in and try it again. Make sure you are pushing/tapping on the moving part and not the stationary piece. Should be another linage from there to the actual carb. Check that it is free and moving easily. Cable problems usually are inside the cabel,rust etc that binds the cable but you should be able to move the actuator w/a pliers with the cable unattached. Good luck

Make sure the chain brake is off (pull it toward you), then remove the bar mounting nut(s)/bolt(s) and the remove the side cover, bar, and chain. Clean the oil passages in the rear of the bar including two small passages that run from the larger holes out to the chain groove on each side. Clean the entire chain groove and make sure the end sprocket turns freely and is well oiled. Clean the engine face where the bar fits, then start the engine. Oil should ooze out of a small port in the engine case. If ok, then lay out the chain so that it can be inspected for bent links, dry/sticking joints, or missing/badly worn drive teeth. Inspect the sprocket on the clutch outer drum component for wear or damaged teeth. Make sure the pitch of the chain teeth match those of the drive sprocket (is this a new chain?). Check the hub bearing of the clutch drum for obvious wear. If all looks good, fit the chain around the clutch sprocket, then slip the bar into the the engine mounting space and work the chain over the entire bar. When setting the outer cover, make sure the adjuster tang fits into the related bar hole, then attach the clamp nut(s)/bolt(s), run up finger tight. Use the adjuster to set the chain tension--it should just pull the lower part of the chain up to the bar plus a little more. Check that you can move the chain by hand without any binding, then tighten the clamp bolts/nuts firmly. Recheck that the chain is properly tensioned. If not, re-loosen the clamp fasteners and re-tension the chain. When the clamp fasteners are tight, the tension must be rechecked. Hope this long-winded response helps!

You probably already tried this stuff already... but id like to offer my 2 cents worth ...

Can you try a penetrating oil product such as Liquid Wrench? Spray it on ... tap (tap with a GOOD rap) the bolt a couple times ... use a long punch and a ball peen hammer. let it set for a while.

Can you get a nut breaker in to that space?

Sometimes, heat will loosen these stubborn nuts but id try the oil first.

Treat with the oil a couple times and let it sit for a while.

Let me know how you make out

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Yes it's the right direction but because of so much heating and cooling those bolts get really tight.Spray alot of penetrating oil (WD-40) on and around the bolts.You may even want to tap the wrench on the bolts in the opposite direction slightly (tighten) to help loosen their adherence,then try the right way to losen them.Dont use a torch! It'll melt the "O" ring on the caliper piston.Take your time

I'd put penetrating oil in it and tap the chuck with a plastic hammer. That should free it up.

Best rgrds, W/D

if chuck is wide open ,look down inside there should be an allen screw or bolt at the bottom of the chuck it should undo anti clocwise and the chuck comes off

They usually put spring washers in there to keep things tight.
Try some good penetrating oil on the pivot bolt.
Last resort--loosen the bolt, use oil on it, retighten.

Did you loosen the nut or bolt that is in the bracket with the alternator? It has tension on it also...