How to trouble shoot Hofner Icon Series Bass

It should still be close to a real Hofner bass
a common wiring configuration is
two pickups volume for each pickup, pickup selector switch,
bass on/off switch, and treb on/off switch
there are quite a few schematics available online...

http://www.hofner-guitars.com/information-service/vintage-wiring-schematics.html?___store=guitar_store_en&___from_store=guitar_store_de

Go to, "vintageguitarpro.com"......You should be able to find your serial number there or put one in. Good luck and hope this helped.

there is a switch in the jack socket that lets it know jack is in use. when the stop working it usually means you need to change the jack, you cannot bend the part back with out breaking it so just best to change it. you can get a replacement jack from ebay, or any electrical supply shop that does small components.

Check that all the eqs are set not to cut bass, check there are no effects on and that the XPQ is off. If you still have the problem how sure are you there is no bass coming from the mixer? Have you tried it with another amp? We had one hire customer who had the same problem you describe and his amp had a crossover and it was set to act as a mid/top amp and wasn't giving him any bass, unsurprisingly, switching it back to full range sorted it.

check the jack wiring, or the battery clip integrity- sometimes the clip wires break but they look fine.

two of the controls are volume, two are tone, (at least usually). the best way to use the controls is to try one at a time till you find the combination that pleases you most. I have been playing bass for 40 years and have 7 bass guitars, two with active pickups and two that acoustic electric

The jack on the guitars is a stereo type jack. The "ring" contact actually is connected to the battery and whenh the PLUG is inserted FULLY it coonects the ring contact of thee jack to the slkeeve contact of the jack which completes the circuit to turn on the battery. Hence while insertying the plug you will firsst get a snap as the tip of the plug ties to the ground of the guitar which is floating and picks up hum. Next the tip will touch the battery connection and get a snap. Finally when fully inserted both the battery is connected as well as the audio.
SOME guitars, especially those with tuners built inj will try tio fire up when the tip (audio) touches the battery cinnection. This may cycle and create the repetitive sound as it tries to start.

No question what to do... take it in under warranty since it is new !!!

You may find that there is a problem with your amp... the seller should be able to test the guitar and demonstrate normal sound for you.

Many users have TOO small of an amp and the distortions make it appear that the guitar is bad... I suspect you will want at least a 12 inch speaker and preferably a 15 inch for your bass.

When low frequency signals drive a speaker too hard it drives the voicecoil out of the linear range and the sound will be irregular..

If it is under warranty, make use of the warranty immediately.

If it is out of warranty it comes down to whether you are adept at electronics.

The cause can be a blown speaker, or something electronic.

The electronic cause would LIKELY be a problem with the input filter caps that cause the voltage to "collapse" under higher load OR a bad power amplifier transistor or chip.

In any case, test equipment will be required to solve the problem.