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There is a way to tell some of the ichidan and godan verbs apart.

If the verb ends in -る and the sound that precedes it is either あ、お、or う, then it is always a godan verb (-うverb).

例 (Example):

やる y/aru = godan verb (○ やります | × やます)
つまる tsum/aru = godan verb (○ つまります | × つます)

ほる h/oru = godan verb (○ のります | × のます)
のぼる nob/oru = godan verb (○ のぼります | × のぼます)

ぬる n/uru = godan verb (○ ぬります | × ぬます)
つる ts/uru = godan verb (○ つります | × つます)

If the verb ends in -る and the sound that precedes it is either い or え, then those are the ones that you have to memorize as they could either be a ichidan or godan verb.

EDIT: Forgot that I could just add it to the usage note. Been so long hahah

Never knew that, interesting!

Thanks - I went ahead and added it into the actual explanation since it's a direct correction to information already in there.

are する　and くる　godan verbs? the vowel sound preceding  る　is う. Or did I misinterpret something? Call me dumb but I'm just confused since it was written under ichidan.

する and くる are best thought of as CRAZY verbs. Or, put another way, する is its own verb type, and くる is its own verb type. They follow their own rules, and should not be grouped with anything else when it comes to usage rules.

ah, it makes sense now.

Maybe it's just my imagination... but I realized, that verbs where the kanji is followed by two (or more) kana are ichidan.
ex.: 伸びる(の.びる) 変える(か.える) 見せる(み.せる) 止める(と.める) 食べる(た.べる) 答える(こた.える) 忘れる(わす.れる) 生まれる(う.まれる)
The potential forms of verbs, which has an e-stem, also has an ichidan conjugation: 読む(よ.む godan)--->読める(よ.める potential, ichidan)

If the kanji of a 3(or more?)-syllable verb is followed by only る it is usually godan.
ex.: 帰る(かえ.る) 参る(まい.る) 辷る(すべ.る)

With this only 2-syllable verbs are still troublesome.

Unfortunately that doesn't always work. for example, with the transitive verbs that you listed, there is always an intransitive pair that goes with it that also has 2 送り仮名 and those verbs are not １段: so in the order you gave, 伸ばす、変わる、止まる all are　5段 verbs

Ah... I understand what you mean, but the verbs you listed are obviously 5段.
I didn't think, I had to point it out since it was clearly explained in the grammar section. Only verbs that end on ~る with a preceding i-sound or e-sound syllable could technically be １段. I was referring to only this group of verbs where it is actually difficult to tell １段 verbs apart from 5段 verbs.

I hope I have expressed myself more clearly now.(^_^;  Do you still see a problem there?