if vibration level and sound are the symptoms of damaged
sprocket, then i dont think my sprocket has any prob. after 10
months riding my bike dont notice anything unusual in the 2 areas.
unless all the way spoil....but dat would mean by now something
would have snapped......aiyah better not joke bout this kind of
thing 
Have you go see your mechanic and ask him to inspect
your gear change pedal lever linkage ? Oh, by the way, when you
engage gear, another mechanism that tensions your chain (chain
tensioner) will be activated. Your last chain was badly worn out
.... could it have been too tight or wat ? Have you asked the
mechanic why the chain was worn badly ? Was the chain used for a
long time already ? If not, shouldn't have worn out very badly. In
any case, in my opinion, the tensioner is
questionable.
actually the bike is my dad's, first edition phantom 150 bought
in '99 and i replaced the chain for the first time only a few
months ago, so i guess safe to say normal wear and tear, although i
not sure how long usually chain can tahan.
actually i all the while planning send to mech, but wif me
personally $$$ is very tight. my purpose in asking around in this
forum is to find out roughly wat the prob is and how much i can
expect to need to fork out before sending to mech. i oso wanna try
suggestions form other ppl experience in case its just a minor
prob. a fren suggested mebbe i need to change the gear box which
will cost as much as engine overhaul according to him; its dat kind
of scenario i scared coz i'll need some time to come up wif dat
kind of money.
appreciate your reply. thanx.