What are the most common problems you guys usually see in your ( or a customer's) reels?
Corrosion without a doubt.
lack of service, no pre use service either. frozen screws ruin everything
Used up/non-carbontex drag washers, over oiling, and as Kamuwela said, "Lack of pre-service"
Dom
Lack of maintanence, frozen screws, and washers not reassembled in the proper order, and my big friend called "frozen pinion on the spool shaft"... ;D :o
Oh and too much grease all over the place and it goes into the gearbox and wets the drag washers. Keep in mind, its not the "shimano drag grease or cals grease", its the blue grease or some other kind of grease not meant to be on the drag washers.
Lucky we have this site to guide us with lots of pictoral examples. People learn in many different ways. I tend to be more visual. I'm a firm believer in pictures speak a thousand words. :)
corrosion!
What's the best way you guys deal with corrosion/rust?
Corosion.
I wash down my gear at the end of the day.
Kamu uses WD40 http://alantani.com/index.php?topic=630.0 in the industrial size container. Seems to work for him to get things cleaned up.