Blowing of woofer MOSFETs

Hi there I am trying to find out about intermittent blowing of the woofer MOSFETs on this unit I have changed them several times and it runs ok for hours then randomly then instantly go short I have changed the diodes on the gates and the two driver chips to no avail I saw that ZEPREP@iso14000 had some info in an older post and mentioned some resistors to change with the FETs so perhaps someone can help as B Ann W technical are useless