After more than 10-15 years, you can be certain that the electrolytic capacitors in your amplifier will have aged, leaked, if not worse, and will not perform at their best, making your amplifier a worse performer.

Some of those capacitor are important because they provide an electrical power reserve when volume peaks are needed, some others are on the signal path, some are within the phono pre-amplifier.

A replacement of those capacitors (a recap) is something that is needed at that stage.

Theory

Here are the capacitors that will need changing on this amplifier, on the schematic diagram:

Power supply capacitors in yellow, signal path capacitors in pink

Here are the capacitors that will need changing on this amplifier, on the wiring diagram:

Power supply capacitors in yellow, signal path capacitors in pink. Red shows the bias adjustment points and variable resistors

In order to visually help, here are a few shots of the real thing. The two main 8200 µF capacitors for the power supply are not shown here, but you can't miss them, they are the biggest things on the board!

Secondary capacitors for the power supply

In red the capacitor for the the right channel amplification, in pink the bias adjustment test points

In red the capacitor for the the left channel amplification, in pink the bias adjustment test points

Here is the list and description of the capacitors to change:

Item	Number	Voltage (V)	Value (µF)	Diameter (mm)	Comments
1. Power Supply
	C903	35	8200	30	10,000 µF 35-40V would be ok too
	C904	35	8200	30	10,000 µF 35-40V would be ok too
	C901	25	2200	16
	C902	25	2200	16
2. Amplification
	C605	100	10	6	Something like Panasonic FC series
	C606	100	10	6	Something like Panasonic FC series
3. Phono stage
	C405	10	4.7	"Bead"	Something like Panasonic FC series, use 10 µF instead
	C406	10	4.7	"Bead"	Something like Panasonic FC series, use 10 µF instead
	C417	50	10	6	Something like Panasonic FC series
	C418	50	10	6	Something like Panasonic FC series

Here are suggestions for replacement, with references from RS Components:

Item	Number	Description	Pack of	Diameter (mm)	RS Stock No	Manufacturer part #	Price	URL
1. Power Supply
	C903	Nichicon Aluminium Electrolytic Capacitor 10000μF 35 V 22mm Through Hole 5101-4 VY Series Lifetime 1000h +105°C	1	22	739-5324	UVY1V103MRD	£3.02	http://uk.rs-online.com/web/p/aluminium-capacitors/7395324/
	C904	Nichicon Aluminium Electrolytic Capacitor 10000μF 35 V 22mm Through Hole 5101-4 VY Series Lifetime 1000h +105°C	1	22	739-5324	UVY1V103MRD	£3.02	http://uk.rs-online.com/web/p/aluminium-capacitors/7395324/
	C901	Nichicon Aluminium Electrolytic Capacitor 2200μF 25 V dc 16mm Through Hole PW Series Lifetime 8000h +105°C	5	16	715-2684	UPW1E222MHD	£4.64	http://uk.rs-online.com/web/p/aluminium-capacitors/7152684/
	C902	Same as above, in the pack of 5					-
2. Amplification
	C605	Nichicon Aluminium Electrolytic Capacitor 10μF 100 V 5mm Through Hole JIS C 5101-1 VY Series Lifetime 1000h +105°C	1	5	862-4190	UVY2A100MDD	£0.24	http://uk.rs-online.com/web/p/aluminium-capacitors/8624190/
	C606	Nichicon Aluminium Electrolytic Capacitor 10μF 100 V 5mm Through Hole JIS C 5101-1 VY Series Lifetime 1000h +105°C	1	5	862-4190	UVY2A100MDD	£0.24	http://uk.rs-online.com/web/p/aluminium-capacitors/8624190/
3. Phono stage
	C405	Nichicon Aluminium Electrolytic Capacitor 10μF 50 V dc 5mm Through Hole PS Series Lifetime 2000h +105°C	5	5	519-4289	UPS1H100MDD	£0.93	http://uk.rs-online.com/web/p/aluminium-capacitors/5194289/
	C406	Same as above, in the pack of 5					-
	C417	Same as above, in the pack of 5					-
	C418	Same as above, in the pack of 5					-
		VAT					£2.42
		Shipping					-
						TOTAL	£14.51