Hi Paul,
Press Down on the lid as much as you can,
http://spapartsnet.com/Popular-Spa-Part ... 0_1_1.html
Then gently tap the grey lock tab of the lock ring counter clockwise while it is in the up position. ( sounds tricky, and it is)
http://spapartsnet.com/Reference-Catalo ... 4_0_1.html
Pull lid straight up, and replace lid o-ring, and or lubricate.
http://spapartsnet.com/Reference-Catalo ... 1_0_1.html
Do not re-seat the lockring as tight as it will go. Tighten it, and back off a hair. Your problem isn't silly, in fact it is very common. I rather enjoy wrestling a good top load can every now and then.
