The drawing of the top sliver down to roving should be straightforward using standard loadings and pinnings for the diameter of the wool and making small adjustments according to the mean fibre length. The quality at each stage can be checked in terms of the Index of Irregularity. Lapping of rollers can arise if the wool is too dry or if there are wet patches, or there is insufficient lubricant/antistat, or if scouring left excessive residuals, or if the rollers have become dirty or degraded.

The generic problem is one of suspected inferior yarn quality and excessive ends-down which have to be compensated for by slowing the spinning speed and, possibly, increasing the twist. The first thing to realise is that yarn properties and spinning performance are quite sensitive to small changes in fibre properties but expected performance can be predicted. However, if performance is below expectations then it can be due to a myriad of causes, for example, machine maintenance (worn rollers, rings, pig-tails or aprons, eccentric spindles, slipping drives, misaligned components, missing ring lubrication etc.) or machine settings (wrong apron spacer, wrong back-draft etc.) or faulty input material (fibre damaged in dyeing, irregular roving, slubs, bad joining etc.) or low moisture content (due to low RH%). Establishing the actual cause of underperformance can take considerable time but firstly requires the ability to measure yarn and fibre properties under standard conditions.

Problems can also become apparent in downstream processing but most should be picked up early if sliver and yarn properties are monitored. Excessive faults in winding can arise from as far back as faulty output webs in combing. Even at winding and two-folding care must be taken because faulty splice settings, or bad knots in two-fold yarn, may show up in weaving.