SGT-DI making strange crackles

[Duroc17]

3 month old AMPEG SGT-DI started making intermittent pops and crackles. Tried different leads. Using just the SGT with the supplied power cable. 
 

Bought from PMT before the closed.  Hoping warranty will still be valid with AMPEG. Have emailed Yamaha UK waiting for reply but AMPEG pedal, doesn’t come up as option in their fault report form 

 

Have sprayed contact cleaner in the outputs. Tried both preamp out and cab sim/phone outputs and still crackles every now and then. 
 

anyone else having problems or may know what’s happening? Failing Yamaha helping will take to my tech guy. Pity as was loving the tone - was planning on getting a Venture V7 head and cab next year to replace this and have just bass - amp - tuner to take out. Might have to bring that forward as got run of gigs coming up.