2 Interesting videos I found on Youtube by some self-made Apple guru: Charles Mangin.
 
First Video: Enhancing a IIe.
The Apple IIe is "enhanced" with more up to date electronics and a lot less fewer chips compared to the original Apple II/II+. But about 1/2 a year later, Apple took it a step further by adding a 65C02 and ROMs with 65C02 commands on it. Later on, they added "Mouse Text" to their Video ROM to use in Apple Works and the Apple Mouse. The Mouse Text Video ROM saves the need of using RAM to add the Mouse Text. But this was not added until the Apple IIe Platinum. Further enhancements to the board was also made from the IIe to the IIe Platinum but this upgrade video (and ordered parts) takes a IIe to a IIe Platinum.
 
It's confusing, and he does not explain it but rather does this "Buy this Enhancement Kit and install it." He does not explain or understand why. In the mid 80s I remember CPU/ROM Upgrades to about 1200 Apple IIe's in the NYC School system and know that the first upgrade did not have a Video (Mouse Text) Upgrade, but a Second Upgrade a couple years later did. This was also a major issue with BAUG (Big Apple Users Group) where many members were split down the middle and many thought the $299 price tag was too much for the upgrade so they made their own.
 
The enhancement also includes the Apple II Mini Assembler, which was on the Apple II/II+ but removed on the unenhanced IIe,  
 
Here is the Video: https://www.youtube.com/watch?v=3tNskimg2iI
Here is the link to buy the upgrade kit: https://www.ultimateapple2.com/catalogzen155a/index.php?main_page=product_info&a mp;cPath=1_16&products_id=14
 
I will need such a kit in the future as my only IIe is not "enhanced." Thought I had 3 IIe's with at least one of them being enhanced, but 2 are MIA, and the one that remains is not enhanced.
 
Second Video: Diagnosing and Repairing your IIgs with a Logic Probe
Though for the IIgs, he explains how to do the same with a II/II+/IIe with just a Logic Probe. It is the Basics of on-board repair without an oscilloscope.
 
Long ago I had a Logic Probe and like most tools, somebody took it.... damn thieves. Can't lend out tools without somebody making off with them. No more - they need tools, they are going have to get their own!
 
Video: https://www.youtube.com/watch?v=Gua_Nv0ouhY