Silly question, but is your original SC/MP an SC/MP II? The original SC/MP only operates up to 1MHz as far as I know. SC/MP II is up to 4MHz, although of course Clive chose to overclock it slightly, mainly because 4.43Mhz crystals were widely used in colour TVs and therefore cheap.
If you can tolerate the delay / risk involved in posting chips back and forth - an activity I know you are no stranger to - I'd be happy to test any suspect ICs in my MK14.
The crystal you can test independently by knocking up a simple logic IC based oscillator like this one, attached, found as a web image. Alternatively just fit any crystal you can find in the range from 1MHz to 4MHz in the MK14 - if your original crystal is at fault the machine will run with any other reasonable crystal frequency, just not at the normal speed.
Also definitely check the states of CPU pins which can halt the CPU, such as RESET and other less obvious ones.
The actual SC/MP datasheet seems quite hard to find, here it is presented in unconventional one-page-at-a-time html format, which is better than nothing.
http://searle.hostei.com/grant/SCMP/index.html
SC/MP applications handbook packed with all sorts of SC/MP information here on bitsavers:
http://bitsavers.trailing-edge.com/c...book-Feb77.pdf