Student loan repayment options

Ok. We have $75k about to go into repayment at 7.6%. I applied for income based repayment, which is $900/month. Wife suggested taking a 401k loan at 4% to save on interest. Max term on the 401k loan is 7 years. This sounds like a bad idea to me, as the payment would go up, plus her 401k would be losing possible market gains.