Ah yes! That got it to work!! While playing with it a bit more, I noticed that as long as I gave it an id, I could use the original code you linked to, where it was calling
You can play with the final results on jsfiddle here.
var chartId = sprite.surface.id;
var chart = Ext.getCmp(chartId); // this works as long as I have some id defined in the chart object, even if I'm not calling it here as I was earlier.
you can now remove the id and instead, use the "this" for accessing the series directly:
you can reduce the code a little by removing the lines related to chart's id. Also, using an id is considered bad practice. you can use component query instead.
Is there a way to change the chart point from a point to an image? I just want to change one of the points though. (in this instance, the last one). Not sure where to look for that info. TIA.