Problem

Possible Cause(s)

Remedy

MARK V won't change speeds from high to low -- or low to high

Control sheave stuck on idler shaft

Floating sheave stuck on motor shaft.

Bent or burred long key in motor shaft.

Motor sheaves mis-aligned.

Free sticking sheave. Lubricate sheave and idler shaft.

Free sticking sheave. Lubricate motor shaft and floating sheave.

Remove key. File off burr or replace key.

Align motor sheaves.

Speed setting creeps up when MARK V is running

Leaf spring under handle doesn't press hard enough against control handle

Speed control bracket bearing worn

Worm gear worn

Remove control handle, gently bend spring up slightly

Replace control bracket

Replace worm gear

Speed dial hard to turn

Sheaves sticking

Foreign matter in quadrant mechanism

Faces of sheaves damaged

Lower sheaves misaligned

Keys on motor or idler shafts damaged

Lubricate sheaves, motor and idler shaft

Clean mechanism

Remove burrs or nicks with fine file

Align lower sheaves

Remove burrs from keys with file -- or replace keys

Speed changes when handle is turned, but speed dial doesn't move

Gears behind handle stripped

Replace either handle, idler gear or speed dial, whichever is worn

Speed dial moves when handle is turned, but speed doesn't change

Control arm quadrant worn

Retaining loop on upper floating sheave disconnected

Control handle mounted improperly on control shaft

Replace control arm quadrant

Connect retaining loop to control arm quadrant

Tighten setscrew in handle so it seats in depression on worm control shaft

Speed dial rattles

Spring under speed dial broken or missing

Repace spring

Speed dial doesn't lay flat in headstock

Screws loose, missing or holes stripped

Tighten or replace screws, if holes are stripped, add nuts

Control handle comes off

Control handle improperly mounted on control shaft

Tighten setscrew in handle so it seats in depression on shaft