Hi Tilda

​Although I don't own an Olivetti 45, looking at some online pictures, it appears to be similar in construction to the Underwood 378, of which I have one. I'll see about lifting the mechanism out of the shell this evening to get a better look at how mine works, then maybe I can give you a few ideas. That being said though, by your description of the problem, it sounds like either the escapement dog assembly is lifting too far so completely disengaging the star wheel, or the floating dog is stuck, broken or missing.

​If the dog assembly is lifting too far, this should be correctable with an adjustment. If the floating dog is stuck, a good deep down internal cleaning is in order. If however the floating dog is broken or missing, then a replacement part is required, this will prove to be a bit more of a challenge. I'm not sure of the disassembly sequence of this model, but you may need to lift the mechanics of the machine out of the plastic base in order to get a better look at the escapement from underneath. If anyone else has experience with this model, please chime in. Hope this points you in the right direction,

Sky

Hi Again Tilda

​With the mechanism out of its case, I had a closer look at my 378. When the carriage is at rest, the star wheel sits against the floating dog and the fixed dog only comes into play when the escapement is tripped by a letter key or the space bar. This would indicate the sear of the fixed dog may be bent or broken off. However, if another member has an Olivetti Lettera 45 and is willing to delve into its workings, this would give us a much better idea of what we're up against.

The only adjustment I can find on the 378 is the escapement bottom stop which controls how far down the dog assembly drops when at rest. If this stop was too low, the carriage would likely zip to the left when the space bar is released. Take the bottom cover off the machine, get a good strong light and see if you can figure out exactly what's happening. All the best,

Sky