The process by which a less familiar spelling of a word is changed ‘logically’ to a more common one is similar to the process known as reanalysis. This is the way in which, over time, people replace an obscure word within a phrase with one that sounds similar but is more understandable and seems to make more sense.
A good example of reanalysis is the development of the phrase ‘to curry favour’, meaning ‘to ingratiate yourself with someone’:
The prime function of an MP is to promote the interests of their constituents, not to curry favour with the party leadership.
The original form of this phrase was actually ‘to curry favel’, which probably sounds rather puzzling. Favel was the name of a chestnut horse in a 14th-century French tale who was renowned for his cunning and duplicity. ‘To curry Favel’ would literally have meant to stroke him or groom him (curry = to groom a horse with a special comb) but the expression came to have the extended meaning ‘to act deceitfully or hypocritically’.
As time passed, the French horse was forgotten and the name ‘Favel’ was replaced by the similar-sounding word ‘favour’, which probably made more sense to later writers than ‘Favel’. The ‘mistake’ was repeated by other writers and eventually it became the accepted form of the phrase.