1) don't plug in til311's upside down. it destroys them. there's a 40 dollar error.
2) momentary switches come in at least two flavors: normally open and normally closed. using the wrong kind (momemtary open) on your reset and slave clear switches keeps your machine in reset.
3) check your caps before you put them in. i ended up desoldering two of them.
4) for a timer, if you don't have the right value cap, use what you got and scale the resistor accordingly to give the same product.
5) the 555's don't have numbers on the silk screen, so you need to follow traces from known resistor names.
6) there aint nothing like an oscilloscope to debug timers.
7) solder 2 opposite corners of each socket, and then, while pushing on the socket, reheat the pins. 'Click' means that there was daylight under the socket.
7) reheat all your solder joints after putting them all in; makes those monster ground connections a bit less ugly,
all in all, pretty smooth.
--curt