Bigguy2017

I have done a few bridge swaps and never noticed a big change in tone as such... There is a change in the envelope of notes with usually an increase in sustain. The really big change was on my Rickenbacker 4003 - this developed the common 'tail lift' , plus the equally common 'folding' of the body at the neck pickup route, which made it unplayable due to a very high action (even with saddles at max low and extra deep string grooves). I swapped it for the Hipshot replacement bridge (brass version to help with neck dive). This is a straight swap using the same screw holes. I flattened the uneven base with emery on a glass plate beforehand and it was a ten minute swap. The lower Hipshot allowed me to drop the action a lot. The difference was quite noticeable - ridiculous sustain - notes ceased to have a 'plucked' envelope and became almost constant like a bass pedal. Result, a massive improvement in playability, not really better 'tone' but certainly a different sound... (a chunk of foam under the strings helped return sustain to something useful). With 'classic' Jazz and P basses I think the BBOT gives a more traditional look and sound - with modern basses I like the Fender 007-000-5124 American Standard 2007 HMV Bass Bridge for ergonomics and function. I never got on with the huge Badass style bridges - mostly as they look crap. 😉 YMMV.

Loose earth somewhere or dead smoothing cap?

'kin 'ell, that's a beaut

So, the speaker output jack works into an external cab? Therefore signal must be present at the jack socket. Take a close look at the speaker out jack socket - if it's the switching type make sure the contacts are closing without a jack in place - push down on the contacts. Pull off the red + blk speaker spade connectors at the PCB end (LS1 + LS2) - with a DVM check for continuity to the speaker. If no DVM then put a AA battery across these terminals - speaker should click... I can't find a schematic for this combo - Ashdown will supply one I'm assume...

Short scale ?

Fender 7250 ?

Remove the valve and check the voltages on the valve socket - carefully... You're looking for +15 VDC on 6+8 (heaters) and +40 to +150 VDC (HT) on pin 4. You have tried another (known good?) valve... If voltages are there, clean and tighten the valve socket contacts (obvs. with power off and drained!) and have a good look for a cracked PCB trace around the valve socket. Measure the values of R2, R12, R13 and C6 - anything open circuit?

The knob is a collet knob. To remove the knob you have to spin the outer brass ring anticlockwise - use a pair of needle nose pliers in the two slots to get it loose. Once the collet is loose the knob will pull off. Then it's a normal pot with a nut + washer - use a spanner...

Nice... matching + contrasting.

Sizes I use are; Fender saddle height screws (Mex + MIJ) ------------------------------------------- M3 grub screws - cone (or cup / dome) point M3 x 10mm M3 x 12mm M3 x 16mm (1.5mm allen key) Fender USA ------------ 1/16" bass (6-32) 0.050" guitar (4-40) www.modelfixings.com (or similar supplier) M3 x 12mm MF-GS37S

Like franzbassist said, best is to buy a selection of screws in Long, Med, Short. Do the bass setup and when you're happy, replace the screws with ones of best length - keep the 'wrong uns' for later use. This plan works best when you have many basses using the same type of screws...

That looks all original spec for Japan.

Hmmm... that looks like the sheared off end of the truss rod