Originally posted by sup
try using about 1-2mm (i think 1mm will do) of fuel tubing as a washer between the chasis and the tank (where the screws pass thru) and tighten it upto a point where there is a little play. this will also reduce the vibrations that the engine makes. if you have spare rubber seals from shock rebuild kits, you may use them as washers too. hope this helps.
Beat me to it! I did that mod last year and haven't had a problem since. No stripped screws and reduction in bubbling tank to boot.