Help, I need suggestions

Whilst not a specialist in this area, if this were me, I'd now look wider than the understanding of and completion of her core role.  Maybe look at:

- Her health and wellbeing - this may/would need to support of a employee support program or someone specialised e.g. her core motivation to work - is she looking for another job, eyesight, what's happening at home - family stresses and strains, is she burning the candles at both ends with an active social life, is there non-prescribed drug taking or high consumption of alcohol happening.   

Her direct working environment - Lighting, seating, desk set-up, location of desk and distractions (like constant noise, or people constantly walking by catching her eye.).

As I said, I'm not a specialist in this area and don't have any solutions.  All I know is there will be a cause there somewhere.  Just a matter of finding it in order to find the right support and solution.    

Angela:

Suggest putting here on a performance improvement plan, if she isn't already, and see whether she is motivated to make a change. This doesn't sound like a training issue. 

First... Thanks for investing in your employee. Nice to see.

As for solutions... PIP for sure as Daniel suggests -  but guessing that's why you're involved already as the (re)training portion of that process.

Also in these situations, the critical question I always ask is if the dip in performance is:

• a) Recent - She was fine before but recently has taken a noticeable turn downward
• b) Mixed - She was always sort on the edge, but lately even worse
• c) Long Term - She has always been below par from the very onset but it was never managed properly and/or management has reached a breaking point with it

Getting an honest (ie non-emotional answer) from the supervisor(s) is key. But when you do, it typically illuminates  how you might proceed.

But in any case, a PIP is likely indicated as a way to get her attention and allow you to bring proper resources/actions to bear..... supportive or otherwise.

Good luck!