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Denon PMA 355 UK problem

I have a Denon 355UK Amp. which has done me very good service and sounds nice mached with my Jamo speakers.
But!! it has just started a problem which is getting very annoying.
It keeps cycling through the input selections by its self?? almost as if someone is pressing the remote! I have eliminated all other remotes by taking and using in the shed at the botom of the garden, without any remotes for a 100yrds and it still does it.
Anyone have any ideas, anyone have a service manual for it?
any help appriciated as I cant afford a new one (or second hand) at the mo, as unemployed after being made redundent a year ago and having several Operations since,


PMA-355 cycling through the input functions.

Hi Jon,

I've had several of these! It seems to be the only problem that this amp suffers.

The problem is dirty contacts on the rotary function switch. This is a bit of a game to get to and involves a major strip-down to the front panel PCB with the switch, there's just no easy way to get to it.

Once you can see it, very carefully drill a 3mm hole in the side of it. Be careful not to let the drill bit slip right inside once you've broken through the plastic casing and try not to let the plastic swarf fall inside.

Once you're there, squirt some switch/contact cleaner inside and give the control some vigorous rotation. DO NOT USE WD40! I use Servisol Super 10 for all of this type of work.

Once reassembled, you should be trouble free for another few years.