Have Shimano SIS Der running 6 speed suntour rear gear cluster.
Indexing works ok but chain occasionly skips if you put a lot of pressure on the small rear cogs.
There is no B screw on the rear der so there is no way of adjusting pully to gear gap which I thought may help alleviate the situation.
Is there another way to adjust the rear der?
Would appreciate any help.
Have you recently replaced the chain, but left the old freewheel on?
You could add a link or two of chain...that will usually allow the derailleur to rise a little. Does the derailleur move freely? Hard to diagnose from the other side of the planet, but I'd say either your drivetrain is shot, or you recently replaced your chain. Cogs and chain wear together. Replace only one and they won't mesh, hence the skipping under pressure....good luck.