I agree with Jaeger it is more likely you BB is loos not the cranks. if you tried to tighten the cranks and BOTH are still loose it is the BB (the axle assembly that the cranks attatch to) a self extractor will not solve this issue.
as for everything else. go bike shopping and look at different bikes. see and ask wht your cycling friends are riding. while you Tange 2 frame is a great riding bike it might be more cost effective to buy something new and leave your Shogun "stock" for pleasure riding.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk