You don't change the oil weight on totems to change the damping.
It's either knackered seals, or too much or too little in the top of the MiCo leg. (possibly as a result of A).
When were the forks last serviced? Also on totems it pays to stick to the lower leg maintenance schedules.
Time to whip them apart for a look-see. Manuals on the RS site, you'll need a syringe (the speedlube one will do) some 5wt and some 15wt fork oil. Some fork grease will help matter along, but not essential. Also a hammer, set of allen keys and a 6 point socket to fit the top cap. Or be VERY carefully with a big spanner, they're made of cheese. If you're half way competent it'll take you an hour or two the first time.