my (left) pedal started creaking and was no longer turning smoothly. Removed pedal and it feels like the bearings that allow the pedal to rotate on the crank threads are gone.

Is this servicable, cost effective etc?

They are Shimano 747's

cheers

I have done on the very first version of SPDs that came out in the early 90's – needed some fairly small spanners tho'.

Even if you open, clean, and repack them with grease, that's gotta be better than nothing.

I believe there's a 'cheat' you can use here by removing the end cap and filling it with grease and putiing it on again, then repeating until the grease has been squeezed right through

Oddly enough cracked open my 540's (I think) for the first time at the weekend as one felt gritty after several years' use. I just undid the locknut on the shaft. Filled with grease and re-tightened – the vision of dirty grease being squeezed out is surpringly very satisfying – and it runs really smoothly now.

I think it was WMB that had an article in a few months back on how to service Shimano SPD's. I followed it, its easy and worth doing.

Someone online I guess…

I think MBR has done it in the past too. It's reasonably straight forward, better now that they have a hex bolt rather than the star nut they used to have.

The proper tool costs £15 and makes it a doddle.

Greasing by way of "grease in pedal body then screw axle assembly back in" is no cheat and if you can't adjust them is better than nothing. A soak/spin/dry in parafin (sp) etc will help.

Parafin or Diesel is magic stuff for cleaning driveline and greasy bearing parts. Love the stuff.