We already knew that the water was getting in (at the front, anyway...

) through the wiper seals, so we'd already ordered a Shumacher kit to replace them. I know this might be boring for some and not trying to teach anyone to suck eggs, but there've been a few folks on here with this problem, so thought they might want to see what's involved. (Bear in mind we're RHD, so some of the dash dismantling might not be the same.)
First step is a bit anal, but a worthwhile tip. Lay some masking tape along the windscreen, level with the top of the wiper blades before you take them off. Sounds stupid, but when you come to put them back on, you'll be glad you did it! Makes it a piece of pee to drop them back on in exactly the right place. Once that was done, the wiper arms came off after a lot of rocking, greasing, penetrating fluid and levering with all sorts of tools....
Next step, drop the steering column down to get some access. The instrument cluster is a bit of a ball ache to get out, but after taking the seat out, access was a lot easier. (Easier, not easy!)
Once you've unscrewed it from the front, you need to get underneath it to pop out the light switch and wiper switch, then disconnect the circuit board and it drops forward just enough to unscrew the alternator indicator nuts.
Try adopting the "Playboy Pose" to get to the rear of the cluster. Worth a laugh and a photo, anyway!

Seriously uncomfortable, though...

24 hours in a day, 24 beers in a case. Coincidence? I think not…
70 Challenger
MMA/489
NSS/435