I don't know how you are painting them but you are getting too much paint on, it isn't the curing temp. The next thing is 200 degrees won't cure those jig, you need about 225 and at that temp they would need to cure for 1.5 hours. If you aren't using a fluid bed you may want to go that route as you will get a thinner more even coat. If you are using a fluid bed then you are holding the jig in the powder too long or you are getting the jig too hot. The last thing is your curing oven, if you are using a toaster oven you'll need to check the temp with an oven thermometer. Toaster ovens, even when brand new, are often off 10 degree or more than what the dial setting is. I had an over that when set at 325 was perfect for curing as the oven thermometer was reading 354 degrees, 29 degrees difference.