I've been down this road with my '93 SSEi.
On mine, I was simply hoping it was the seal where the pump fits into the reservoir, but that wasn't the problem on mine. Both pumps leaked internally, in the area where the pump shaft is exposed.
I temporarily used a sealant on the outside of the motor housing, over the open area where the motor shaft is exposed (I placed a piece of rubber or another material over the opening before applying the sealant so the shaft could still spin) but that only stopped the leak for a few months.
I eventually replaced the entire tank with one from a junker, and haven't had a problem since.
'99 Bonneville SLE, white, 112,000 miles
'02 Park Avenue Ultra, white diamond pearl, 88,000 miles