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PE is the single most difficult thing to get rid of IMO. When you think about it, when everything is aligned, tied down, balanced focused and sweet, the last remaining source of error is that darned motorised RA drive (price paid for living on a rotating planet).
I spent years battling with the residual PE in an LX200, and it is still a problem for me using a high end research mount engaged in SNe research (can't use autoguiding in survey work).
PE will usually always show up as 'egg shaped stars' (in the east / west direction) in long exposures. PEC will get rid of some, but not all of the wobble - and sometimes PEC can introduce it's own 'drift over time'. Jumping stars are often likely to be non-PE based (unless you have a really bizarre worm) and could be dirt, damaged worm etc. Wind usually accounts for less frequently observed issues - but if you're constantly imaging under windy conditions it could well be a factor.
The key is to tackle each issue in isolation. Do your best to fine tune your mechanics (worm / gear mesh etc.). Tie that 'scope down, lock down the optics (and focuser) camera etc. Make sure you're aligned with the pole. Once you have removed all of the possible variables, you stand a half decent chance of characterising and then fixing any RA wobble you have left over.
At the end of the day, there will always be some residual wobble. If it's obvious (and ruining your astrophotos) it's time to consider a better mount, or a focal reducer.
Have fun,
Paul
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