Bosch POF 600A secondhand, but treat it to a new collet.
The motors are Swiss made and excellent quality. The 500A is almost identical but cheaper as it isn't varispeed. I have both (one from new) and can confirm that the plunge is rubbish (the base casting is too flimsy, and I think the plunge rods move slightly) but they are lightweight and easy to handle, and the plunge is irrelevant for a dovetail jig. They take 8mm collets too (I have one). Spares from Miles Tools and Machinery Centre (MTMC) in Yeovil.
The motor units fit to the plunge base with a collet/clamp areangement. There is a 40mm collar (from memory) on the motor, making it very easy to fit to a jig, for example as a horizontal router, or on a pantograph for pattern following.
I also have a Trend auxiliary, "universal" base for mine, which takes a range of bushes (Axminster do an inexpensive set of different sizes), This is occasionally very handy, especially as you can centre the bushes very accurately on the shaft (this works for other routers too). You don't say if your jig uses a guide bush or a bearing (I don't have Leigh, but I think they made both types), but it would probably be slightly easier with a bearing-guided cutter - I am always a bit nervous that the bushes might move slightly, as the Trend plate is cheaply moulded (not a router problem though!).
Otherwise wot Pete said above!
E.
PS: I am quite a bit younger than you, but I have arthritis in my hands. I find the handles comfortable, which isn't true forc every power tool I have!
