Gravity is your friend in this case- - - - -I'd spend more time working from the top, but a little squirt through the fill hole won't hurt. Once it's well-soaked with penetrant, some vigorous movement with the shifter will probably be the best approach.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!