While alliteration has a very old pedigree in English and is the source of innovation in phraseology (despite blatant redundancies, cf. the odious binomials skill set and price point, to name only two contemporary cases), paronomasia has been neglected as a source of false analogy that gives rise to variant pronunciations. The American English rendering of the word machination(s) with the sound [ʃ] instead of [k] for –ch-, while manifestly produced by analogy with machine, should probably not be attributed solely to the influence of the latter, as will be made clear below.

The Oxford English Dictionary Online has the following entry for this word:

machination, n. An instance of plotting or (usually malicious) contrivance; an intrigue, plot, or scheme. Now usu. in pl.
Pronunciation: Brit. /ˌmakᵻˈneɪʃn/, /ˌmaʃᵻˈneɪʃn/, U.S. /ˌmækəˈneɪʃən/, /ˌmæʃəˈneɪʃən/. Etymology:  < Anglo-Norman and Middle French machination plotting, wicked contrivance or stratagem (13th cent. in Old French) and its etymon classical Latin māchinātiōn-, māchinātiō machine-making, piece of machinery, stratagem (rare in this sense in classical Latin, although attested in post-classical Latin in British sources from 960) < māchināt-, past participial stem of māchinārī + -iō. Compare Italian macchinazione plot, machine, siege engine (14th cent.), Catalan maquinació plot (late 14th cent.). The pronunciation with /ʃ/, due to the influence of machine n., was recorded in Webster (1961); the presence of an entry in the B.B.C.’s Recommendations for Pronouncing Difficult Words (S.P.E. Tract No. XXXII, 1931), p. 28, recommending the traditional pronunciation, may be indirect earlier evidence for the existence of the pronunciation with /ʃ/.”

Besides the influence of machine, one should also consider the same sort of paronomastic interference that has produced a derived meaning, in American English, for the verb meld, namely ‘mixing together’, even though the original meaning was ‘announce’ and had nothing to do with ‘mixing’. The new meaning is the product of conflating meld with weld, i. e., where only the initial consonant need be interchanged for the new sense to ensue. In the case of machination(s), the false analogy stems from the sound-alikes mesh (cf. enmesh) and (much less-likely) mash. The original sound of the Anglo-Norman word is undercut by its etymologically inauthentic association with a verb that suggests something like what takes place in and results from a plot, intrigue, or malicious contrivance.