To get any seriously useful help at a distance, you'll need to supply
more information.  I know nothing of the Seeburg L, but have a fair
amount of general electrical and organ knowledge.

Has the fault occurred immediately upon restoration, or after some use?
In what condition is the internal wiring of the instrument?  Was it
renewed as part of the restoration?  Does the blower-motor run?  If it
runs at all, does it appear to run at normal speed?  Is the wind supply
an original bellows or a high-speed fan?  Under what circumstances does
the 5-amp protection fail, on first start-up or after the motor has
been running for a while?  Does the motor show signs of overheating? 
And have you tried running the motor itself off-load by removing
driving-belts or disconnecting cranks?  Have you checked whether the
whole mechanism has any stiff or seized bearings?  Does the motor
spindle turn freely by hand if the load is uncoupled?

Of what nature is the 5-amp protection?  When you refer to "main fuse,"
do you mean one fitted inside the instrument or one on your household
distribution board?  Did the restoration retain a fuse, or was a
circuit-breaker installed in its place?  (A breaker of the same rating
as a fuse is more sensitive and can trip if it doesn't like the motor's
power-factor.)

Can you be certain the fault is due to the driving-motor, and not to
other circuitry such as player-action or decorative lighting?  Is the
blower motor AC or DC, or universal?  If DC-only, what type of start-up
control does it have?  And if DC, presumably you have some sort of
converter or rectifier to power it from AC mains; is the converter OK
off-load?

If the motor is AC and single-phase, can you tell its type (universal,
shaded-pole, capacitor-start or capacitor-run)?  (A shaded-pole motor
will normally run hotter than the other types.)  If the motor is
original, it may have an obsolete form of start-up provision.  The
ratings plate may specify the type.

Is the player action pneumatic or electrical?  If the latter, is it
powered by motor-generator or transformer-rectifier?  Or by a generator
driven from the blower motor?

There are numerous possible causes of failure depending on the answers
to the foregoing.  You may have an insulation failure in any of the
electrical circuitry.  This may be intermittent and affected by
temperature and/or atmospheric humidity, or even be caused by vibration
from the mechanism.  There may be shorted windings in the motor (and/or
converter or transformer).  If the motor is of capacitor-run type the
capacitor may have shorted or failed open-circuit.  In the former case
the motor may start but will continue to draw maybe four times its
running-current and rapidly overheat.  In the latter case the motor
will not start at all.  The motor will also overheat if mechanical
overload prevents it from running at normal speed.  If the motor is of
capacitor-start type and the capacitor is OK, the motor's centrifugal
switch may be failing to cut out the start-winding when the motor has
come up to speed.  The motor will run but will draw excessive current
and rapidly overheat.

I know an actual case of a one-horse-power single-phase AC motor on a
fan blower which continually trips its breaker if the motor-casing is
earthed (grounded).  It never blew the fuse it formerly used.  If the
ground connection is removed, the breaker does not trip.  Nonetheless
no leakage current can be measured between windings and casing.  My
guess is that the breaker is too sensitive to power-factor.  Has your
household power-supply been recently updated?

If the motor is AC and original it may have been designed for a
different mains frequency from present-day standard (60Hz in USA).  If
the design frequency was significantly different, the motor will run
less efficiently at the wrong speed, but I wouldn't expect this to
cause failure.

I hope the foregoing may be of some use.  But essentially, to fix the
fault you need to know the nature of all the electrical components, and
try to establish at exactly what stage in the instrument's start-up or
running the fuse fails or the breaker trips.

Barrie Land
UK