Senor Don -
Did you smear heat-sink paste between the module and the alu heat sink that forms part of the mounting bracket on the side of the dizzy? The modules must be heat-sensitive, as the work shop manual stipulates that this is necessary.
Other than that point, I can offer no other 'wisdom' regarding your problem. La Paz is quite high, so maybe the modules run hotter at higher altitudes (but that doesn't make sense to my very limited knowledge of electronics, so the thought is probably a red herring).
By the way, what symptoms does the fault express? I ask because we once had a 110 V8 with twin SUs plus a pointless dizzy, and we ended up with a problem (never fully resolved, although we have subsequently sold the vehicle) whereby the engine would intermittently loose power after running for an hour or so. We replaced fuel filters, plugs, checked ignition cables, replaced the module (yes) - nothing would sort the problem. As I had rebuilt the SUs quite some time before then, I could only guess that the problem was perhaps related to a stretched timing chain (something I hadn't yet got around to replacing).
Good luck!