Don, there are some contradictions between my stats and yours. Well:

Are you sure that Ugo - Ugo, not Udo - Prini was on the island? Did he practice the course? This interests me much, so let me know, Don!. I have only Pietro Ghersi as Guzzi's rider in 1926.

Luigi Arcangeli was only a Bianchi's rider and not a Guzzi, according my stats.

Tazio Nuvolari - the greatest ever rider - was on the Island together with the Bianchi's team but he did NOT practice the course in any way on a racing machine because of his left hand's poor conditions. I think that this was said also on the italian magazine "Motociclismo", that sent a journalist on the island to follow the TT races since 1924. Larry, am I right??

About Pietro Ghersi's race, yes, he was formally second at the end of the race, beaten by the great irish rider Paddy Johnston on a Cotton machine. Ghersi had been first for the first six laps (the race was a 7 laps one) but during the last lap he had a plug change (I think the plug chnage happened on the roads and not at the pits, can you confirm?) and then a pit stop for refuelling the bike.

The Ghersi's affaire was really a stroke for the italian motorycling. But just the year after the TT organizers were received as guests for the 1927 "Circuito del Lario", the so called "Italian TT".