OsCommerce Credit Class/Gift Voucher fix

I have a broken Credit Class/Gift Voucher install. Currently, the first time a valid coupon code is entered it is rejected. The second time it is accepted. If the customer logs out (session closes), they would have to enter it twice again next time they login. I think the problem is somewhere in the ot_coupon payment module, not sure. The Credit Class/Gift Voucher contribution has been modified to not ask for credit card information if the coupon code entered covers the entire balance due, it does not load any payment modules. I would like this fixed ASAP.