Hello Hen,
A very basic survey of the Aller Mine engine house was undertaken by a chap called Damian Nance in the early 1990s, published in volume 13.2 of Mining History which I had the pleasure of editing. It is available on the web at:
http://www.pdmhs.com/BackIssues.asp There's also a short piece about the mine in Stafford Clark's Mining and Quarrying in the Teign Valley (1995). More info is also available in Schmitz (1980) The Teign Valley Silver Lead Mines published as a volume of British Mining. Also, see K Hamilton Jenkin's MInes of Devon (1981). There's certainly a copy of both the latter in Newton Abbot and Exeter libraries as also is the aforementioned Dines. Sorry I can't send you excerpts but its quite a lot of text. The OS 25-inch 1st edition map of 1888 is quite informative too and shows extensive mining remains around your area, including shafts, spoil heaps and buildings.
Hope this is some help. I could certainly find some more bits and pieces if you're interested to dig deeper.
I've done archaeological surveys of several other engine houses around Dartmoor myself but have never made it up to the Teign valley lead mines. I don't live far from you at Newton Abbot so I'd be very keen to come and have a look around if you'd allow it.
All the best
Can't understand 'ow I got the sack boay, I burnt twice s'much coal as they other stokers