How to change a dip tube<br>Check when your water heater was manufactured. Nearly all gas and electric water heaters manufactured between 1993 and 1997 were installed with defective dip tubes. The dip tubes were made of a material that quickly degraded and disintegrated, causing dip tube failure.
Dip tubes made after 1997 weren't defective as often
The context only says dip tubes were often defective in that time frame, not after.
( z1 defective :polarity - :domain ( z2 tube :mod ( z3 dip ) :ARG1-of ( z4 make :time ( z5 after :op ( z6 date-entity :year 1997 ) ) ) ) :frequency ( z7 often :ARG2-of ( z8 have-degree :ARG1 z2 :ARG3 ( z9 equal ) ) ) )