Hi. I purchased a pair of large Advents from my nephew. They needed refoaming , so I did that. They sound awesome on my Sansui G3000. The question I have is this. Do I need to clean the rear speaker wire contacts with anything? Also, the board the speaker connectors are connected to is loose on one of the speakers. How do I reattach? The third question is, how do you recommend cleaning the yellowing on the original grill covers?