Bicycle Mechanics - Clicking noise on a shimano pd-m520 pedal

All,
The left pedal on bike makes a clicking noise. It's when the pedal hits between 11 an 10 o'clock (looking at it from the left, crank is moving counter clock wise)
It seems to get progressively worse (noisier) over time amd now I can feel the click as well

I looked at the pedals and could not see a difference between the left and reight pedals

Questions:
1. Are these pedals maintainable? I didn't see any obvious ways of pulling them apart
2. You think I should replace them? I am planning to do RAGBRAI in july (470 miles in 7 days) and don't want to have a failure at that time

Thanks for any insights
Duppie

Here (http://bike.shimano.com/media/techdocs/content/cycle/EV/actionsports/PD/EV-PD-M520-2235_v1_m56577569830608614.pdf) is the exploded view. There is a special tool for disassembly. Haven't pulled mine apart yet but have read elsewhere it isn't difficult. I would either replace or rebuild before your event.

It doesn't HAVE to be your pedals. Could easily be something else (bb, chainring bolts, crankarms, etc., etc).

You many find the following links helpful in tracking it down:

http://sheldonbrown.com/creaks.html

AND

http://www.parktool.com/repair/readhowto.asp?id=123

It's usually just a matter of patiently removing, cleaning,
re-lubricating, and re-torquing fasteners until it quiets down.

Have you tried new cleats or at least lubing the cleats/pedals with some White Lightning dry chain lube?

You may need to service the pedal, but you can also remove the pedal and clean the spindle threads and the crank threads, grease, and put back on. Also, as Ray Dockrey stated, lubing the pedals/cleats may also help.

I have these pedals and both methods have helped to mitigate similar problems I have experienced.

I wanted to thank anyone who responded. You guys saved me $50 by not buying a new set of pedals.
I went to the LBS this weekend on an unrelated issue and mentioned the pedal noise.
They said they pedal hardly ever causes problems, but that they would look at tightening the crank

Guess what!. Yesterday I rode 45 miles and the noise had disappeared. You guys thought of it first!

Thanks, Duppie

Thank you neil0502. The links are very helpful