964 leaking tail light assemblies

Vehicle Information: Year: 1989; Body Type: Coupe; Engine (type, size, modifications): 3.6 stock; Total Mileage: 125000;

Water is entering the rear tail light assemblies on both sides eventually burning out the bulbs. I can't seem to see how water is getting in. The seals seem intact; breather hoses connected etc. I've replaced the seal on the left side to no avail.