PPM is just fine as some have indicated. I have experienced glitching from various sources and have always been able to resolve it. The cause of a few of my glitching experiences are:

1.)small crack in aluminum boom support (vibrating metal)
2.)anodizing worn off on pinion radiating RF on tail drive wire
3.)defective gyro (interference in rx from gyro control wire)
4.)loose screw on aluminum boom support (vibrating metal)

Most of the glitches I have ever had were a quick momentary glitch that did not prohibit landing the helicopter.

Some glitching has lead me to suspect damage (notched bearings) in the main shaft bearings, starter shaft bearings and engine bearings but have never been proven since I would just replace notchy bearings as they were discovered.

Hope this helps,
GOODDAY!