It is hard to say without knowing your skill set, generators combine need for mechanical ability with electronic and electrical ability and if you make a mistake they have the ability to injure or kill you in a number of ways. Having said that just about anyone with basic electronics skills can likely repair a faulty AC voltage regulator (note there is also a DC battery charging regulator on these generators which is sealed in an epoxy blob) as it is a reasonably simple circuit, and there are trouble shooting instructions in the TM, I have not read the ones for the MEP-002 lately, but I do know the ones for the voltage regulator in the MEP-016 family require a reasonably well stocked electronics repair bench. If you don't have access to a full electronics repair bench, the next best option is the shotgun approach, changing out the most likely suspects. On the MEP-002a the most likely suspect is the output transistor, this part ( commercial version is a 2N3584, original is mil spec JAN2N3584 or JANX2N3584, these cost 5-10 times the commercial part cost, and are the same thing, just with higher levels of fault testing ) sells for $5-$10 online (can sometimes be found on ebay, also check with Mouser.com )and is fairly simple to change. It is about the size of a dime and has 2 pins soldered to the board, plus it is held on by a pair of small screws and nuts. Someone that is moderately skilled with a soldering iron can change it in about 5-10 minutes (I did it on mine a month ago, and am far from an expert with a soldering iron), note diodes can be harmed by heat so certain precautions need to be done, like backing with a heat sink (pliers) and quick taps with a hot soldering iron to limit heat transfer. If the output transistor is not he problem then it would be time to move on to the capacitors, etc.
Ike
p.s. the frequency meter on this is really a 2 part system, the frequency transducer mounted in the center at the back of the control box, and the display gauge. Problems with the transducer are common, the gauge is a simple low amp style deflection gauge with a custom face plate, you can test the output of the transducer with a common multimeter. If you don't want to try tackling the front panel instruments now, there are a couple of cheap work arounds, one is a Kill-A-Watt P4400 (don't get the fancier ones, some don't have the Hz meter) that sells for about $20, another is a small volt/Hz meter sold on ebay by Hardy Diesel that displays volts / Hz on a red LED display, also about $20. If you have a multimeter it may have a Hz function, just be aware many of the cheaper models may get confused by generator power and give crazy readings, so if it is not something like a good Fluke meter, be wary of insane Hz readings.
opcorn: