a little stuck on participles.

I propably should have asked this question earlier, but here goes. I am slowly gettin the gist of wheelocks chapter 22 and 23. Slowly. However I am a little stuck on participles.
I was told by my latin professor to memorize the perfect stem and the fourth principle part. He told me they didn’t follow the same rules that you find with the first two principle parts. Well that’s a lot too memorize and while I find that I have most of the principle parts of the verbs memorized I can’t seem to form the participles with any ease. I’m not sure what my hangup is. So here’s the question.

Based on the first little bit of the verb, not sure what you call it but in Laudo ladare laudatus sum it would be the laud

same with vis, ag, aud, What is the easiet way to get from A to b with participles short of completely going back and commiting each participle to memory.

for example
Ago Agere egi actum why does ago change to actus a um and how can I more easily spot the changes based on the first part of the verb (vis, ag, audm et cetera) what transformation takes place that will get me from A -B more easily.

I’m afraid there isn’t really a good, reliable shortcut to memorizing the four principal parts. They are principal parts becuase you need ALL of them to be able to form all the forms of the verb. If it were possible to figure out the fourth principal part from the others with 100% reliability, then it wouldn’t be a principal part!

That said, the first conjugation usually follows the pattern you recognized:
-ô, -âre, -âvî, -âtus

It would’ve been best to memorize ALL the parts as you went along. At this point, your best bet is probably to go back and relearn the additional principal parts.

The reason why I asked is there seem to be a vocal pattern to the parts of speech I think I am missing it somewhere. The whole time I have been studying latin the key has been on the tip of my tounge but I can’t seem to communicate my question. But it seems certain vowels are changed into other vowels based upon the surrounding consontants and vice versa. That is why I asked the question.

For example

timeo timere timui

and contineo continere continintus. differ in the course of an I or an E.

The same can be said of I stem nouns of the third declesnion. Some vowels are changed and some vowels remain the same. However If I knew the rules for pronounciation a little better I think I would have a better time.

There is a pattern. You’re right that in early Latin the verbs assimilated and contracted in different ways. If you made yourself an expert in Latin language evolution, you could probably do a pretty good job guessing the principal parts. But you’re much better off spending your time trying to memorize them. The pattern will make it easier, I think.