Thanks Paul. It seems there are not too many Hurricane owners about, not a great deal of love for the game! I think I've learned to love it. HaLet us know how you get on.
From what you say it doesn't seem to be ghosting if everything else in the matrix is off other than the 4 dim rows.
Although the program doesn't allow the delay to be extended it's definitely possible if required.
From reversing the Hurricane code I see an additional access to the lamp row driver which isn't part of the lamp mux update function. This bit of code hasn't had the CLR opcode replaced so if it gets called it'll certainly cause a glitch on the lamp row driver. Whether or not that's the problem I don't know.
If other investigations fail to reveal anything it could be patched and tried to see if it helps the issue.
You would've thought others with this game would've mentioned this problem.
I'll see if I can find someone else to have a check, with LEDs...
It seems strange that it's 4 specific rows that are dim..
Can voltage "leak" into a row on the matrix.and light the lot?