In example 1, you state this:
This is in reference to North's hand. However, North is not holding Left-Ace. He is holding Left-10 with an ace in next. Hearts is trump in this example. The overall concept is correct (the guarded left being a guaranteed trick) but the play-by-play confuses the ace of next with the ace of trump.Would you overtrump trump the queen? Holding the left - ace already assures your team that your opponents won't make two points on this hand. Is there a possible way to euchre them? This is the perfect opportunity to rid your hand of an unneeded card, the 9 of diamonds. Your team has one trick and you hold a second one in your hand. If your partner can get a trick, it's euchre time.
In example 2, you state this:
West does not lead the 9 of diamonds in this example. East does. East took the previous trick by trumping his partner's ace.Now West, seeing that the maker just threw off a diamond, leads back the 9 of diamonds. The maker(S) takes the trick with the ace. The maker's next lead is the ace of clubs. The hope of course, is to have it go through. If not, it will draw out some trump. The ace does walk. This gives the maker's team their first trick.
These are both minor errors and the overall concepts are easily understandable but it may be a good idea to further improve understanding by fixing them.