85 380 SL Seat Guides and Sunvisor questions

[Dynamo]

So I have a 1985 380SL that I need to get up to snuff for the summer. I am going to reupholster the seats in MB-Tex from WorldUpholstery. While I am at it I am going to take care of a few other things that I have some questions on.

1. Adjusting the seats forward and backward are a real pain as they are very hard to move. What is the cause of this? I think it may be the plasic guides that everyone mentions when taking the seat out to upholster it. If so, I can easily replace these when I am upholstering the seats. If not what may be the cause?

2. My Sun Visors look like crap and spray out a fine mist of rust from one too many times getting wet. I would love to replace them, but everywhere I go they price out the visors at a couple hundred bucks. Is this right?? Where is a cheap place to get new visors?

Thanks for any help!!

Cheers,
Nick