Some Lynx games start up & show game title screen but then go no further

[ticman31]

I've just taken down my Lynx 2 from my parents loft for the 1st time in 25 years & initially all the games came up with the 'Insert error' message. I have cleaned them all with contact cleaner & 9 games load fine now but 4 of them only go as far as the title screen & either go blank or freeze on the opening option screen. (Gates of Zendecon will show the title screen & then go blank but the music will be playing in the background). Can anyone please suggest what could be causing this after I have given the contacts a good clean? Many thanks for your assistance. 

[xhul]

Are there more signs of track corrosion on those 4 carts than on the others?
Also, i guess it wouldn't hurt to blow some air on the socket itself, in case some dust accumulated inside, which could make some contacts fail even more.