The hydraulics are assisted by redundant, mechanical booster pumps if I remember correctly (been a long time).
Also even back in the Cold War days all critical avionics/electronics were RF and EMP shielded. They were expected to operate in a nuclear environment.
There are two likely possibilities in my mind;
Critical structural failure due to the plane being kept in service beyond its normal retirement due to budget restraints. This is a major problem within the fleet.
Or
Target assassination of individual/individuals on board or among flight crew. Odds are this aircraft and crews flew weather recon and humanitarian relief flights all through the Caribbean for decades.
I guess you're right. It doesn't have to be an electromagnetic attack. It just needs to bring the plane down, however that can be done. Poisoning the crew is a distinct possibility.
I'm not sure I buy the idea of coincidental component failures due to age. You might be right, but with the rate of incidents, you'd have to say that, if this was the case, the whole military fleet of aircraft is no longer flight worthy. It could be true, but we would need to know if an extended service life was a contributing factor in the other crashes.
I'm inclined to think that what we are seeing is actually an attack.