orthography - How was the letter -u- written in Old English?

I was reading the etymology for 'come (v.)' when I encountered:

[...] The substitution of Middle English -o- for Old English -u- before -m-, -n-, or -r- was a scribal habit before minims to avoid misreading the letters in the old style handwriting, which jammed letters. The practice similarly transformed some, monk, tongue, worm. Modern past tense form came is Middle English, probably from Old Norse kvam, replacing Old English cuom. [...]

Are there any illustrations or depictions of texts, to help me visualise and discern how this problem of misreading caused this morphological substitution (from -u- to -o-)? I Googled to no avail.

Answer

In the notes of the Wikipedia article about minims, there's a link to the work of Heidi Harley, an author who supports the idea you transcribed, that is, that some spellings came from the scribes writing words differently to avoid confusion in minim clusters. Among other interesting things, the work says, in pages 292-93, that

The letters u, i, v, w, m, and n were all written using a sequence of a particular short downstroke of the quill, called a minim (the word minim itself would have been written using only minims). When several letters made of minims came in sequence, they were exceptionally hard to decipher. Was it an i and an m, or two ns?
Consequently, in some frequent words spelled with sequences of these letters, a convention arose whereby one of the offending vowels was changed to an o, so that the vowel-consonant sequence was clear. In general, this caused little pronunciation difficulty, because the words were common enough that everybody could just recognize them. Some words whose spellings were affected this way were woman (originally wimman), come (originally cume) and love (originally luve).

You can also find a picture exemplifying the minims in that page.