How to access back of fuse block

[ettabetta]

All 4 power windows on my daughter's 1990 LeSabre suddenly stopped working. I replaced the power seat circuit breaker with the window one and the seat works so I know the breaker is still good. When I was going to put the window circuit breaker back in I noticed that only one of the connectors where the prongs of the circuit break plug into was visible. It appears the the other connector has come out of whatever holds it in place and fallen back behind the fuse block somewhere. It that possible? and if so how do I take the fuse block assembly out so I can see it?

Thanks,
Bruce