hiwatt maxwatt g100r troubles!

[pasciu666]

Hello everyone.. i've got this Hiwatt SS amp and one nigth while playing it just suonded stronger for an instant and than shot to silence.. after the show, at home i tried it again an di noticed that for the first 30 seconds it sounds well, than the clean suond start having a noise in background, almost saturating while playing at low dinamics,  than if i play even a string at the normal strenght i use it make this peak of volume than it shut up.. any idea?
sorry if my english is poor, i hope you understand something of this!!
thanx! :tu:

[J M Fahey]

1) try this amp with another speaker.
2) hit the top of the amp with your fist: does it cut off? ... or reversely, does it come alive?
3) slightly move jacka and pots, any results?
4) plug a known good guitar cable from send to receive of the effects loop, or from preamp out to power amp in.
Post results.